Assertion(A): The radiation from the sun’s surface varies as the fourth power of its absolute temperature.
Reason (R): According to Stefan’s Law  $E=\sigma T^4$, where, E = energy radiated per unit area in unit time
 

Assertion is true and Reason is false

Both Assertion and Reason are true and Reason is not the correct explanation of Assertion

Assertion is false and Reason is true

Both Assertion and Reason are true and Reason is the correct explanation of Assertion