Stars a and B Have the Same Radius, but the Spectrum

Multiple Choice

Stars A and B have the same radius, but the spectrum of star A peaks at a wavelength of 500 nm, whereas star B's spectrum peaks at 1000 nm. What is the ratio of the energy flux leaving the surface of star A to the energy flux leaving the surface of star B?

A) 1/16
B) 1/4
C) 4
D) 16