Task: Class Definition Understanding (ontology: Earth_Environment/OBOE)

Which of the following definitions best describes 'Conductance'?

A. the concept, radiant emittance, and radiant exitance are radiometry terms for the power per unit area of electromagnetic radiation at a surface. "the concept" is used when the electromagnetic radiation is incident on the surface. "Radiant exitance" or "radiant emittance" is used when the radiation is emerging from the surface. The SI units for all of these quantities are watts per square meter (W/m2) (wikipedia). All of these quantities characterize the total amount of radiation present, at all frequencies. It is also common to consider each frequency in the spectrum separately. When this is done for radiation incident on a surface, it is called spectral the concept, and has SI units W/m3, or commonly W·m−2·nm−1.
B. measures how easily electricity flows along a certain path through an electrical element. The SI derived unit for electrical the concept is the siemens
C. The number of photons striking an area per unit time. This could be probably also be called a PhotonArealDensityRate.
D. the concept is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through or is emitted from a particular area, and falls within a given solid angle. The SI unit for the concept is candela per square metre (cd/m2).

Answer: measures how easily electricity flows along a certain path through an electrical element. The SI derived unit for electrical the concept is the siemens