Calculate the amount of energy emitted by the Earth. Given σ = 5.67 x 10⁻8 Wm⁻2K⁻⁴.
a) 1.23 x 10¹⁷ W
b) 3.78 x 10²⁶ W
c) 1.23 x 10¹⁵ W
d) 5.67 x 10⁸ W