Two identical photocells are illuminated by the same monochromatic beam (ν>ν0) of intensity I. In photocell X, 30 % of the light is reflected by the metal surface, but the remaining photons eject electrons with quantum efficiency 60 %. In photocell Y, no light is reflected, but the quantum efficiency is only 40 %. What is the ratio Isat(X) : Isat(Y) of their saturation currents?
a) 3:2
b) 21:20
c) 7:4
d) 20:21