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: pounds per square inch is the pressure units of which system of measurement? 
Knowledge Triplets: Pressure, measurement_unit.dimension.units, Torr
US customary units, measurement_unit.measurement_system.volume_units, Cubic foot
Pressure, measurement_unit.dimension.units, Kilopascal
US customary units, measurement_unit.measurement_system.weight_units, Ounce
pounds per square inch.noun.01, base.wordnet.synset.word, m.07szl6q
US customary units, measurement_unit.measurement_system.temperature_units, Degree Rankine
Dram, measurement_unit.mass_unit.measurement_system, US customary units
Pressure, user.avh.default_domain.ellerdale_topic.ellerdale_id, 0080-fe72
Pressure, base.ontologies.ontology_instance.equivalent_instances, m.07nfhwr
US customary units, measurement_unit.measurement_system.volume_units, Oil barrel
US customary units, measurement_unit.measurement_system.pressure_units, Pounds per square inch
united states customary system.noun.01, base.wordnet.synset.equivalent_topic, US customary units
Bushel (US), measurement_unit.volume_unit.measurement_system, US customary units
m.019h, type.permission.controls, m.0qtb8dl
Square yard, measurement_unit.area_unit.measurement_system, US customary units
Pounds per square inch, user.avh.default_domain.ellerdale_topic.ellerdale_id, 00d8-e1f9
pounds per square inch.noun.01, base.wordnet.synset.hypernym, pressure unit.noun.01
pounds per square inch.noun.01, base.wordnet.synset.word, m.07szl73
Pressure, measurement_unit.dimension.units, Technical atmosphere
Gallon (US), measurement_unit.volume_unit.measurement_system, US customary units
Grain, measurement_unit.mass_unit.measurement_system, US customary units
US customary units, user.movgp0.default_domain.measurement_system.unit_of_volume, Gallon (US)
Pounds per square inch, measurement_unit.pressure_unit.pressure_in_pascals, 6894.75729
Mile, measurement_unit.distance_unit.measurement_system, US customary units
US customary units, measurement_unit.measurement_system.volume_units, Gallon (US)
m.040b101, type.permission.controls, Service Pressure
US customary units, measurement_unit.measurement_system.weight_units, Pound
US customary units, user.movgp0.default_domain.measurement_system.unit_of_power, Mechanical horsepower
US customary units, measurement_unit.measurement_system.volume_units, Gill
g.125_pcvh0, base.schemastaging.pronunciation.yomigana, じゅうりょうポンドまいへいほうインチ
Degree Fahrenheit, measurement_unit.temperature_unit.measurement_system, US customary units
Cental, measurement_unit.mass_unit.measurement_system, US customary units
Peck (US), measurement_unit.volume_unit.measurement_system, US customary units
Square mile, measurement_unit.area_unit.measurement_system, US customary units
US customary units, user.movgp0.default_domain.measurement_system.unit_of_temperature, Degree Rankine
US customary units, measurement_unit.measurement_system.length_units, Yard
Force and energy, base.skosbase.skos_concept.narrower_topic, Pressure
US customary units, measurement_unit.measurement_system.volume_units, Pint (US)
US customary units, measurement_unit.measurement_system.weight_units, Short quarter
Miles per hour, measurement_unit.speed_unit.measurement_system, US customary units
pounds per square inch.noun.01, base.wordnet.synset.syntactic_category, Noun
Gallon, measurement_unit.volume_unit.measurement_system, US customary units
Pressure, measurement_unit.dimension.units, KiloNewton per metre squared
micro per degree F, measurement_unit.inverse_temperature_unit.measurement_system, US customary units
Pint (US), measurement_unit.volume_unit.measurement_system, US customary units
US customary units, measurement_unit.measurement_system.length_units, Mile
m.0t7dyxc, dataworld.gardening_hint.last_referenced_by, m.0qtb8dl
US customary units, measurement_unit.measurement_system.volume_units, Quart (US dry)
US customary units, measurement_unit.measurement_system.weight_units, Grain
m.07szl73, base.wordnet.word_sense.sense, pounds per square inch.noun.01
US customary units, measurement_unit.measurement_system.speed_units, Miles per hour
US customary units, measurement_unit.measurement_system.length_units, Foot
Pressure, measurement_unit.dimension.units, Megapascal
Foot-lambert, measurement_unit.luminance_unit.measurement_system, US customary units
Pressure, measurement_unit.dimension.units, Pounds per square inch
Pressure, measurement_unit.dimension.si_base_unit, Pascal
Square foot, measurement_unit.area_unit.measurement_system, US customary units
US survey acre, measurement_unit.area_unit.measurement_system, US customary units
Short quarter, measurement_unit.mass_unit.measurement_system, US customary units
Pressure, measurement_unit.dimension.units, Inch of mercury
Oil barrel, measurement_unit.volume_unit.measurement_system, US customary units
Mechanical horsepower, measurement_unit.power_unit.measurement_system, US customary units
US customary units, measurement_unit.measurement_system.volume_units, Peck (US)
Ounce, measurement_unit.mass_unit.measurement_system, US customary units
m.0qtb8dl, dataworld.gardening_hint.last_referenced_by, Pounds per square inch
Pressure, measurement_unit.dimension.units, Kilopound-force per square inch
Fluid ounce (US), measurement_unit.volume_unit.measurement_system, US customary units
US customary units, user.movgp0.default_domain.measurement_system.unit_of_lenght, Foot
Service Pressure, type.property.unit, Pounds per square inch
m.07nfhwr, base.ontologies.ontology_instance_mapping.freebase_topic, Pressure
Service Pressure, type.object.permission, m.040b101
Fluid Dram US, measurement_unit.volume_unit.measurement_system, US customary units
US customary units, measurement_unit.measurement_system.volume_units, Cubic mile
pressure unit.noun.01, base.wordnet.synset.hyponymy, pounds per square inch.noun.01
US customary units, measurement_unit.measurement_system.volume_units, Quart (US)
US customary units, measurement_unit.measurement_system.area_units, Square mile
Cubic mile, measurement_unit.volume_unit.measurement_system, US customary units
pounds per square inch.noun.01, base.wordnet.synset.gloss, a unit of pressure
m.075_72n, base.yupgrade.user.topics, Pressure
US customary units, measurement_unit.measurement_system.length_units, Inch
Foot, measurement_unit.distance_unit.measurement_system, US customary units
Quart (US dry), measurement_unit.volume_unit.measurement_system, US customary units
Intermediate Pressure, type.object.permission, m.040b101
US customary units, user.movgp0.default_domain.measurement_system.unit_of_speed, Miles per hour
Pressure, measurement_unit.dimension.units, Centimetre of water
Pressure, measurement_unit.dimension.units, Pièze
Service Pressure, type.property.unique, true
pressure unit.noun.01, base.wordnet.synset.equivalent_topic, Pressure
Short ton, measurement_unit.mass_unit.measurement_system, US customary units
US customary units, measurement_unit.measurement_system.temperature_units, Degree Fahrenheit
US customary units, user.movgp0.default_domain.measurement_system.unit_of_volume, Quart (US)
US customary units, measurement_unit.measurement_system.specific_heat_capacity_units, Btu per pound-mass per degree F
US customary units, measurement_unit.measurement_system.area_units, Square foot
Pressure, measurement_unit.dimension.units, Atmosphere
US customary units, user.movgp0.default_domain.measurement_system.unit_of_volume, Pint (US)
Pounds per square inch, base.schemastaging.context_name.pronunciation, g.125_pcvh0
US customary units, user.movgp0.default_domain.measurement_system.unit_of_lenght, Yard
Rod, measurement_unit.distance_unit.measurement_system, US customary units
pressure.noun.01, base.wordnet.synset.equivalent_topic, Pressure
US customary units, measurement_unit.measurement_system.luminance_units, Foot-lambert
US customary units, measurement_unit.measurement_system.length_units, Chain
US customary units, measurement_unit.measurement_system.pressure_units, Kilopound-force per square inch
US customary units, user.movgp0.default_domain.measurement_system.unit_of_lenght, Inch
US customary units, user.avh.default_domain.ellerdale_topic.ellerdale_id, 0080-aff7
Cubic foot, measurement_unit.volume_unit.measurement_system, US customary units
US customary units, user.movgp0.default_domain.measurement_system.unit_of_lenght, Mile
Pressure, measurement_unit.dimension.units, Millibar
Kilopound-force per square inch, measurement_unit.pressure_unit.measurement_system, US customary units
m.019h, type.permission.controls, m.0tct220
Pressure, base.skosbase.vocabulary_equivalent_topic.broader_concept, Force and energy
m.040b101, type.permission.controls, Intermediate Pressure
US customary units, user.movgp0.default_domain.measurement_system.unit_of_temperature, Degree Fahrenheit
Service Pressure, type.property.expected_type, Floating Point Number
noun.quantity, base.wordnet.lexical_name.synsets, pounds per square inch.noun.01
US customary units, measurement_unit.measurement_system.weight_units, Dram
m.0tmwcs_, dataworld.gardening_hint.last_referenced_by, m.0tct220
First Stage Regulator, type.type.properties, Intermediate Pressure
pounds per square inch.noun.01, base.wordnet.synset.lexname, noun.quantity
US customary units, measurement_unit.measurement_system.weight_units, Short ton
Service Pressure, type.property.schema, Scuba Tank
m.0tct220, dataworld.gardening_hint.last_referenced_by, Pounds per square inch
US customary units, measurement_unit.measurement_system.inverse_temperature_units, micro per degree F
pounds per square inch.noun.01, base.wordnet.synset.equivalent_topic, Pounds per square inch
US customary units, measurement_unit.measurement_system.length_units, Link
united states liquid unit.noun.01, base.wordnet.synset.broader_topic, US customary units
Intermediate Pressure, type.property.schema, First Stage Regulator
US customary units, measurement_unit.measurement_system.volume_units, Fluid ounce (US)
Quart (US), measurement_unit.volume_unit.measurement_system, US customary units
m.0v8c53n, dataworld.gardening_hint.last_referenced_by, Pressure
m.0n5sspb, dataworld.gardening_hint.last_referenced_by, US customary units
US customary units, measurement_unit.measurement_system.volume_units, Gallon
Pressure, measurement_unit.dimension.units, Gigapascal
Inch, measurement_unit.distance_unit.measurement_system, US customary units
Chain, measurement_unit.distance_unit.measurement_system, US customary units
US customary units, measurement_unit.measurement_system.power_units, Mechanical horsepower
François Arago, user.lindenb.default_domain.scientist.known_for, Pressure
Pint (US dry), measurement_unit.volume_unit.measurement_system, US customary units
Degree Rankine, measurement_unit.temperature_unit.measurement_system, US customary units
Link, measurement_unit.distance_unit.measurement_system, US customary units
Gill, measurement_unit.volume_unit.measurement_system, US customary units
US customary units, user.movgp0.default_domain.measurement_system.unit_of_area, Square mile
US customary units, user.movgp0.default_domain.measurement_system.unit_of_mass, Pound
Pressure, medicine.disease_cause.diseases, Pressure ulcer
US customary units, user.movgp0.default_domain.measurement_system.unit_of_volume, Fluid ounce (US)
Pressure ulcer, medicine.disease.causes, Pressure
US customary units, measurement_unit.measurement_system.length_units, Rod
Yard, measurement_unit.distance_unit.measurement_system, US customary units
Scuba Tank, type.type.properties, Service Pressure
Pressure, measurement_unit.dimension.units, Bar
Intermediate Pressure, type.property.expected_type, Integer
Intermediate Pressure, type.property.unit, Pounds per square inch
Pressure, measurement_unit.dimension.units, Barye
Pressure, base.schemastaging.context_name.pronunciation, g.125_s3xp2
US customary units, measurement_unit.measurement_system.area_units, US survey acre
US customary units, measurement_unit.measurement_system.area_units, Section
m.0qtb8dl, type.object.permission, m.019h
US customary units, measurement_unit.measurement_system.area_units, Square yard
US customary units, user.movgp0.default_domain.measurement_system.unit_of_area, Square yard
Pressure, measurement_unit.dimension.units, Pascal
US customary units, user.movgp0.default_domain.measurement_system.unit_of_area, Acre
US customary units, measurement_unit.measurement_system.volume_units, Bushel (US)
m.0tct220, type.object.permission, m.019h
US customary units, user.movgp0.default_domain.measurement_system.unit_of_pressue, Pounds per square inch
Btu per pound-mass per degree F, measurement_unit.specific_heat_capacity_unit.measurement_system, US customary units
Pound, measurement_unit.mass_unit.measurement_system, US customary units
Integer, type.type.expected_by, Intermediate Pressure
Pressure, measurement_unit.dimension.units, Decibars
Pressure, measurement_unit.dimension.units, Kilogram-force per square centimetre
US customary units, measurement_unit.measurement_system.weight_units, Cental
Floating Point Number, type.type.expected_by, Service Pressure
Section, measurement_unit.area_unit.measurement_system, US customary units
US customary units, measurement_unit.measurement_system.volume_units, Pint (US dry)
m.07szl6q, base.wordnet.word_sense.sense, pounds per square inch.noun.01
Pounds per square inch, measurement_unit.pressure_unit.measurement_system, US customary units
US customary units, measurement_unit.measurement_system.volume_units, Fluid Dram US

Answer: US customary units