FRET Technique Question

In the FRET technique, what happens when the donor and acceptor fluorescent groups approach each other closely?

a)The fluorescence intensity of the donor rises while the fluorescence intensity of the acceptor drops.
b)The fluorescence intensity of the donor rises, while the fluorescence intensity of the acceptor rises.
c)The fluorescence intensity of the donor is reduced, while the fluorescence intensity of the acceptor rises.
d)The fluorescence intensities of both the donor and the acceptor group drop.

I already answered the question with choice B and I got it wrong, so it is not that option.