Solar constant for Earth is 2.0 cal per cm$$^2$$ per minute. [1 cal = 4.2 J]. Angular diameter of the Sun (as seen from the Earth) is $$\frac{1^\circ}{2}$$ (= half a degree). Treating Sun as a black body, its surface temperature is estimated to be nearly

A

6000 K

B

5800 K

C

6200 K

D

5500 K