Answer: C. illuminance of a surface.
a) Incandescence: The phenomenon of light emission by a body as a result of high temperature.
B. Luminous flux : It is the quantity of the energy of the light emitted per second in all directions.
C. Illuminance of a surface :describes the quantity of light emitted by a light source or received at a surface.
D. luminous intensity : the quantity of visible light that a point source radiates in a given direction.