user: You are a structured reasoning expert tasked with solving problems step by step. 
You first think about the reasoning process in the mind and then provide the answer. The reasoning process and answer should be enclosed within <think> </think> and <answer> </answer> tags, respectively, i.e., <think> reasoning process here </think> <answer> answer here </answer>. 
Given a question and the associated knowledge graph triplets (entity, relation, entity), you are asked to answer the question with these triplets and your own knowledge. 
You can break down the original question into several sub-questions and explore the given knowledge graph to solve them step-by-step. If there are multiple possible answers, choose one as the final answer. 
After thinking, when you finally reach a conclusion, clearly state the answer within <answer> </answer> tags, i.e., <answer> answer here </answer>. 
Question: coulomb per cubic metre refers to what unit? 
Knowledge Triplets: International System of Units, measurement_unit.measurement_system.time_units, Nanosecond
International System of Units, measurement_unit.measurement_system.time_units, Centisecond
Mole, measurement_unit.substance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.time_units, Microsecond
International System of Units, measurement_unit.measurement_system.speed_units, Metre per second
International System of Units, measurement_unit.measurement_system.catalytic_activity_units, Katal
decasecond, measurement_unit.time_unit.measurement_system, International System of Units
Gigabit per second, measurement_unit.unit_of_data_transmission_rate.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.length_units, Hectometre
Joule per kilogram, measurement_unit.specific_energy_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.time_units, Millisecond
Milliwatt, measurement_unit.power_unit.measurement_system, International System of Units
Kilosecond, measurement_unit.time_unit.measurement_system, International System of Units
Newton metre, measurement_unit.force_moment_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.thermal_conductivity_units, Watt per meter per kelvin
International System of Units, measurement_unit.measurement_system.specific_energy_units, Joule per gram
International System of Units, measurement_unit.measurement_system.pressure_units, Gigapascal
petasecond, measurement_unit.time_unit.measurement_system, International System of Units
Newton, measurement_unit.unit_of_force.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.volume_units, Milliliter
Picometre, measurement_unit.distance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.time_units, zeptosecond
Newton per metre, measurement_unit.surface_tension_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.potential_units, Volt
Square meter, measurement_unit.area_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.permittivity_units, Farad per metre
International System of Units, measurement_unit.measurement_system.specific_energy_units, Joule per kilogram
Coulomb per cubic metre, measurement_unit.dimension.units, Electric charge density
Unit of Electric Charge Density, type.type.properties, Density in coulombs per cubic meter
International System of Units, measurement_unit.measurement_system.volume_units, Cubic kilometer
Volt per metre, measurement_unit.electric_field_strength_unit.measurement_system, International System of Units
Becquerel, measurement_unit.radioactivity_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.solid_angle_units, Steradian
Centisecond, measurement_unit.time_unit.measurement_system, International System of Units
Kilogram per square metre, measurement_unit.unit_of_surface_density.measurement_system, International System of Units
Kilojoule, measurement_unit.energy_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.electric_field_strength_units, Volt per metre
International System of Units, measurement_unit.measurement_system.length_units, Nanometre
Tesla, measurement_unit.magnetic_flux_density_unit.measurement_system, International System of Units
Kilogram per cubic metre, measurement_unit.unit_of_density.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.resistivity_units, Ohm meter
International System of Units, measurement_unit.measurement_system.pressure_units, Kilopascal
Watt per meter per kelvin, measurement_unit.thermal_conductivity_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.volume_units, Deciliter
Ampere per metre, measurement_unit.magnetic_field_strength_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.temperature_units, Kelvin
International System of Units, measurement_unit.measurement_system.energy_density_units, Joule per cubic metre
Megawatt, measurement_unit.power_unit.measurement_system, International System of Units
zeptosecond, measurement_unit.time_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.power_units, Milliwatt
International System of Units, measurement_unit.measurement_system.force_units, Newton
International System of Units, measurement_unit.measurement_system.time_units, petasecond
International System of Units, measurement_unit.measurement_system.time_units, decisecond
International System of Units, measurement_unit.measurement_system.luminous_intensity_units, Candela
Joule, measurement_unit.energy_unit.measurement_system, International System of Units
m.0qrbg_1, dataworld.gardening_hint.last_referenced_by, International System of Units
Kilojoule per mole, measurement_unit.molar_energy_unit.measurement_system, International System of Units
Density in coulombs per cubic meter, type.object.permission, m.014_
Centiliter, measurement_unit.volume_unit.measurement_system, International System of Units
Electric charge density, measurement_unit.dimension.si_base_unit, Coulomb per cubic metre
Radian, measurement_unit.angle_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.molar_volume_units, Cubic metre per mole
International System of Units, measurement_unit.measurement_system.length_units, Megametre
Kilometer, measurement_unit.distance_unit.measurement_system, International System of Units
Estelle, base.yupgrade.user.topics, International System of Units
Milliliter, measurement_unit.volume_unit.measurement_system, International System of Units
Density in coulombs per cubic meter, type.property.unit, Coulomb per cubic metre
Joule per gram per kelvin, measurement_unit.specific_heat_capacity_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.conductance_units, Millisiemens
Kilowatt, measurement_unit.power_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.electric_charge_density_units, Coulomb per cubic metre
Square kilometer, measurement_unit.area_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.volume_units, Liter
Kilohertz, measurement_unit.unit_of_frequency.measurement_system, International System of Units
m.014_, type.permission.controls, Density in coulombs per cubic meter
International System of Units, measurement_unit.measurement_system.current_density_units, Ampere per square metre
Metre per second, measurement_unit.speed_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.acceleration_units, Metre per second squared
International System of Units, measurement_unit.measurement_system.viscosity_units, Pascal second
International System of Units, measurement_unit.measurement_system.amount_concentration_units, Micromolar
Cubic metre per second, measurement_unit.unit_of_volumetric_flow_rate.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.data_rate_units, Megabit per second
International System of Units, measurement_unit.measurement_system.inverse_temperature_units, Inverse Kelvin
Gray per second, measurement_unit.absorbed_dose_rate_unit.measurement_system, International System of Units
Femtosecond, measurement_unit.time_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.molar_energy_units, Joule per mole
Cubic metre, measurement_unit.volume_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.radiant_intensity_units, Watt per steradian
International System of Units, measurement_unit.measurement_system.time_units, Picosecond
International System of Units, measurement_unit.measurement_system.area_units, Square meter
International System of Units, measurement_unit.measurement_system.illuminance_units, Lux
International System of Units, measurement_unit.measurement_system.length_units, Kilometer
International System of Units, measurement_unit.measurement_system.amount_concentration_units, Nanomolar
Hectometre, measurement_unit.distance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.time_units, yoctosecond
International System of Units, measurement_unit.measurement_system.irradiance_units, Watt per square metre
International System of Units, user.avh.default_domain.ellerdale_topic.ellerdale_id, 0080-5e5f
International System of Units, measurement_unit.measurement_system.weight_units, Kilogram
Farad, measurement_unit.capacitance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.length_units, Picometre
Joule per gram, measurement_unit.specific_energy_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.length_units, Meter
International System of Units, measurement_unit.measurement_system.amount_concentration_units, Mole per cubic metre
International System of Units, measurement_unit.measurement_system.absorbed_dose_rate_units, Gray per second
International System of Units, measurement_unit.measurement_system.absorbed_dose_units, Gray
Millisiemens, measurement_unit.conductance_unit.measurement_system, International System of Units
Watt per square metre per steradian, measurement_unit.radiance_unit.measurement_system, International System of Units
Ampere, measurement_unit.current_unit.measurement_system, International System of Units
Gigapascal, measurement_unit.pressure_unit.measurement_system, International System of Units
Sievert, measurement_unit.dose_equivalence_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.length_units, Decametre
Candela per square metre, measurement_unit.luminance_unit.measurement_system, International System of Units
zettasecond, measurement_unit.time_unit.measurement_system, International System of Units
Millimeter, measurement_unit.distance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.length_units, Decimetre
Millisecond, measurement_unit.time_unit.measurement_system, International System of Units
Microsiemens per centimeter, measurement_unit.unit_of_conductivity.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.volume_units, Centiliter
Nanosecond, measurement_unit.time_unit.measurement_system, International System of Units
Joule per mole per kelvin, measurement_unit.molar_heat_capacity_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.molar_energy_units, Kilojoule per mole
yoctosecond, measurement_unit.time_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.power_units, Kilowatt
International System of Units, measurement_unit.measurement_system.resistance_units, Ohm
International System of Units, measurement_unit.measurement_system.time_units, yottasecond
Centimeter, measurement_unit.distance_unit.measurement_system, International System of Units
Gray, measurement_unit.absorbed_dose_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.time_units, Kilosecond
International System of Units, measurement_unit.measurement_system.angle_units, Radian
International System of Units, measurement_unit.measurement_system.volumetric_heat_capacity_units, Joule per cubic metre per kelvin
hectosecond, measurement_unit.time_unit.measurement_system, International System of Units
Megapascal, measurement_unit.pressure_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.time_units, Attosecond
International System of Units, measurement_unit.measurement_system.surface_density_units, Kilogram per square metre
Deciliter, measurement_unit.volume_unit.measurement_system, International System of Units
Microgram, measurement_unit.mass_unit.measurement_system, International System of Units
Metre per second squared, measurement_unit.acceleration_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.frequency_units, Megahertz
International System of Units, measurement_unit.measurement_system.data_rate_units, bit per second
International System of Units, measurement_unit.measurement_system.electric_flux_density_units, Coulomb per square metre
Molar, measurement_unit.amount_concentration_unit.measurement_system, International System of Units
Nanometre, measurement_unit.distance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.data_rate_units, Gigabit per second
Cubic metre per kilogram, measurement_unit.specific_volume_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.temperature_units, Degree Celsius
International System of Units, measurement_unit.measurement_system.time_units, zettasecond
International System of Units, measurement_unit.measurement_system.area_units, Square kilometer
Katal per cubic metre, measurement_unit.catalytic_concentration_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.catalytic_concentration_units, Katal per cubic metre
Joule per cubic metre per kelvin, measurement_unit.volumetric_heat_capacity_unit.measurement_system, International System of Units
Decametre, measurement_unit.distance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.data_rate_units, Terabit per second
terasecond, measurement_unit.time_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.angular_acceleration_units, Radian per second squared
Joule per kilogram per kelvin, measurement_unit.specific_heat_capacity_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.time_units, decasecond
Electric charge density, measurement_unit.dimension.units, Coulomb per cubic metre
Liter, measurement_unit.volume_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.specific_volume_units, Cubic metre per kilogram
Megasecond, measurement_unit.time_unit.measurement_system, International System of Units
Coulomb per kilogram, measurement_unit.exposure_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.data_rate_units, Kilobit per second
Coulomb per square metre, measurement_unit.electric_flux_density_unit.measurement_system, International System of Units
Picosecond, measurement_unit.time_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.luminous_flux_units, Lumen
International System of Units, measurement_unit.measurement_system.dose_equivalence_units, Sievert
Farad per metre, measurement_unit.permittivity_unit.measurement_system, International System of Units
Lumen, measurement_unit.luminous_flux_unit.measurement_system, International System of Units
Weber, measurement_unit.magnetic_flux_unit.measurement_system, International System of Units
Joule per mole, measurement_unit.molar_energy_unit.measurement_system, International System of Units
Watt per square metre, measurement_unit.irradiance_unit.measurement_system, International System of Units
bit per second, measurement_unit.unit_of_data_transmission_rate.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.luminance_units, Candela per square metre
International System of Units, measurement_unit.measurement_system.time_units, Femtosecond
Milligram, measurement_unit.mass_unit.measurement_system, International System of Units
Kilogram, measurement_unit.mass_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.substance_units, Mole
Density in coulombs per cubic meter, type.property.schema, Unit of Electric Charge Density
Decimetre, measurement_unit.distance_unit.measurement_system, International System of Units
Radian per second, measurement_unit.angular_velocity_unit.measurement_system, International System of Units
Ohm centimeter, measurement_unit.unit_of_resistivity.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.length_units, Millimeter
International System of Units, measurement_unit.measurement_system.magnetic_flux_units, Weber
International System of Units, measurement_unit.measurement_system.heat_capacity_units, Joule per kelvin
Second, measurement_unit.time_unit.measurement_system, International System of Units
micro per degree C, measurement_unit.inverse_temperature_unit.measurement_system, International System of Units
Cubic kilometer, measurement_unit.volume_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.magnetic_field_strength_units, Ampere per metre
Coulomb per cubic metre, measurement_unit.electric_charge_density_unit.measurement_system, International System of Units
Nanomolar, measurement_unit.amount_concentration_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.molar_heat_capacity_units, Joule per mole per kelvin
International System of Units, measurement_unit.measurement_system.volume_units, Hectoliter
Megabit per second, measurement_unit.unit_of_data_transmission_rate.measurement_system, International System of Units
Ohm, measurement_unit.resistance_unit.measurement_system, International System of Units
Attosecond, measurement_unit.time_unit.measurement_system, International System of Units
Steradian, measurement_unit.solid_angle_unit.measurement_system, International System of Units
Hectoliter, measurement_unit.volume_unit.measurement_system, International System of Units
Joule per kelvin, measurement_unit.heat_capacity_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.weight_units, Microgram
International System of Units, measurement_unit.measurement_system.current_units, Ampere
International System of Units, measurement_unit.measurement_system.weight_units, Tonne
International System of Units, measurement_unit.measurement_system.time_units, Second
Floating Point Number, type.type.expected_by, Density in coulombs per cubic meter
Terabit per second, measurement_unit.unit_of_data_transmission_rate.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.volume_units, Cubic metre
International System of Units, measurement_unit.measurement_system.exposure_units, Coulomb per kilogram
International System of Units, measurement_unit.measurement_system.time_units, Megasecond
International System of Units, measurement_unit.measurement_system.capacitance_units, Farad
Meter, measurement_unit.distance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.frequency_units, Gigahertz
International System of Units, measurement_unit.measurement_system.energy_units, Joule
International System of Units, measurement_unit.measurement_system.weight_units, Milligram
Pascal second, measurement_unit.viscosity_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.surface_tension_units, Newton per metre
International System of Units, measurement_unit.measurement_system.time_units, terasecond
Siemens, measurement_unit.conductance_unit.measurement_system, International System of Units
Henry, measurement_unit.inductance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.angular_velocity_units, Radian per second
Kilometres per second, measurement_unit.speed_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.pressure_units, Megapascal
International System of Units, measurement_unit.measurement_system.magnetic_flux_density_units, Tesla
International System of Units, measurement_unit.measurement_system.volumetric_flow_rate_units, Cubic metre per second
International System of Units, measurement_unit.measurement_system.energy_units, Kilojoule
Density in coulombs per cubic meter, type.property.expected_type, Floating Point Number
International System of Units, measurement_unit.measurement_system.time_units, hectosecond
Watt, measurement_unit.power_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.frequency_units, Hertz
Candela, measurement_unit.luminous_intensity_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.specific_heat_capacity_units, Joule per gram per kelvin
International System of Units, measurement_unit.measurement_system.time_units, exasecond
Tonne, measurement_unit.mass_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.specific_heat_capacity_units, Joule per kilogram per kelvin
Radian per second squared, measurement_unit.angular_acceleration_unit.measurement_system, International System of Units
Reciprocal metre, measurement_unit.wavenumber_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.permeability_units, Henry per metre
International System of Units, measurement_unit.measurement_system.resistivity_units, Ohm centimeter
International System of Units, measurement_unit.measurement_system.frequency_units, Kilohertz
International System of Units, measurement_unit.measurement_system.length_units, Centimeter
Kelvin, measurement_unit.temperature_unit.measurement_system, International System of Units
Gigasecond, measurement_unit.time_unit.measurement_system, International System of Units
Megahertz, measurement_unit.unit_of_frequency.measurement_system, International System of Units
Gram, measurement_unit.mass_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.power_units, Megawatt
yottasecond, measurement_unit.time_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.speed_units, Kilometres per second
Hertz, measurement_unit.unit_of_frequency.measurement_system, International System of Units
Coulomb, measurement_unit.charge_unit.measurement_system, International System of Units
Micromolar, measurement_unit.amount_concentration_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.radiance_units, Watt per square metre per steradian
Mole per cubic metre, measurement_unit.amount_concentration_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.conductance_units, Siemens
Kilopascal, measurement_unit.pressure_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.inductance_units, Henry
Degree Celsius, measurement_unit.temperature_unit.measurement_system, International System of Units
Microsecond, measurement_unit.time_unit.measurement_system, International System of Units
Density in coulombs per cubic meter, type.property.unique, true
Watt per steradian, measurement_unit.radiant_intensity_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.radioactivity_units, Becquerel
International System of Units, measurement_unit.measurement_system.conductance_units, Microsiemens
exasecond, measurement_unit.time_unit.measurement_system, International System of Units
Cubic metre per mole, measurement_unit.molar_volume_unit.measurement_system, International System of Units
Pascal, measurement_unit.pressure_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.time_units, Gigasecond
decisecond, measurement_unit.time_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.density_units, Kilogram per cubic metre
Kilobit per second, measurement_unit.unit_of_data_transmission_rate.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.power_units, Watt
International System of Units, measurement_unit.measurement_system.amount_concentration_units, Molar
Joule per cubic metre, measurement_unit.energy_density_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.inverse_temperature_units, micro per degree C
International System of Units, base.schemastaging.context_name.pronunciation, g.125_p8yyr
Volt, measurement_unit.potential_unit.measurement_system, International System of Units
Megametre, measurement_unit.distance_unit.measurement_system, International System of Units
Coulomb per cubic metre, measurement_unit.electric_charge_density_unit.density_in_coulombs_per_cubic_meter, 1.0
Henry per metre, measurement_unit.permeability_unit.measurement_system, International System of Units
Ampere per square metre, measurement_unit.current_density_unit.measurement_system, International System of Units
Katal, measurement_unit.catalytic_activity_unit.measurement_system, International System of Units
Micrometer, measurement_unit.distance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.wavenumber_units, Reciprocal metre
Inverse Kelvin, measurement_unit.inverse_temperature_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.charge_units, Coulomb
Siemens per meter, measurement_unit.unit_of_conductivity.measurement_system, International System of Units
Ohm meter, measurement_unit.unit_of_resistivity.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.length_units, Micrometer
Kilometres per hour, measurement_unit.speed_unit.measurement_system, International System of Units
Lux, measurement_unit.illuminance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.speed_units, Kilometres per hour
Gigahertz, measurement_unit.unit_of_frequency.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.pressure_units, Pascal
International System of Units, measurement_unit.measurement_system.weight_units, Gram
Microsiemens, measurement_unit.conductance_unit.measurement_system, International System of Units
International System of Units, measurement_unit.measurement_system.force_moment_units, Newton metre

Answer: Electric charge density