We're interested in knowing the rate at which light energy is received by a unit of area on a particular surface, we're really trying to figure out the a. luminous flux. b. illuminance of a surface. c. incandescence. d. luminous intensity.

B. illuminance of a surface.

Explanation:

A. Luminous flux is the quantity of the energy of the light emitted per second in all directions.  

B. Illuminance of a surface describes the quantity of light emitted by a light source or received at a surface.

C. Incandescence is The phenomenon of light emission by a body as a result of high temperature.

D. luminous intensity is the quantity of visible light that a point source radiates in a given direction.

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it is b. absorbs thermal energy