The thermal radiation emitted by a body in proportional of Tⁿ where T is its absolute temperature. The value of n is exactly 4 for all bodies.
According to Stefan-Boltzmann Law:
The energy of thermal radiation emitted per unit time by a body having surface area A is given as:

Here, e (between 0 to 1) is the emissivity of the body and σ is the Stefan-Boltzmann constant and T is the Temperature.
For black body, e=1.
Thus, option (b) is the correct option.