Radiant heat is proportional to fourth power of absolute temperature

Emissive power depends on temperature

Emissive power and absorptivity are constant for all bodies

Ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body.

D. Ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body.