Radiant Energy from the Sun Reaches the Earth at a Rate

Radiant energy from the Sun reaches the Earth at a rate of 1.70 $\times$ 10¹⁷ W.When 30% of the radiant energy is reflected and 70% absorbed,the average temperature of the Earth's atmosphere is 253 K or -20 $^{\circ}$ C.If the atmosphere absorbed 100% of the solar radiant energy,then what is the average temperature of the Earth's atmosphere?

A) 2.5 $^{\circ}$ C
B) 2.8 $^{\circ}$ C
C) 3.0 $^{\circ}$ C
D) 3.6 $^{\circ}$ C
E) 4.6 $^{\circ}$ C