$A$ wire of length $L$ and diameter $d$ is used in a bulb. The temperature of the wire is $T$ and the power radiated by the wire is $P$. Its emissivity is $e$ ($\sigma$ = Stefan's constant). (Assume that the emissivity of the wire material is the same at all wavelengths).

• A
  $\frac{P}{\sigma T^4 \pi d L}$
• B
  $\frac{P}{\sigma T^2 \pi d L}$
• C
  $\frac{P}{\sigma T^2 \pi d^2 L^2}$
• D
  $\frac{P^2}{\sigma T^4 \pi d L}$