To Maximize the Number of Thymine Dimer Mutations Following UV

To maximize the number of thymine dimer mutations following UV exposure, should you keep a plate of fungal cells in the dark, in the light, or does it matter at all?

A) The dark-light will activate the photorepair systems that can break thymine dimers induced by UV light.
B) The light-it's important to keep on producing the thymine dimers by keeping the plate exposed to light as much as possible.
C) It's best to alternate light and dark every hour to increase the chances that thymine dimers will form in the fungal cells, but still keep the photorepair systems from correcting them as they are formed.
D) It doesn't matter-fungal cells don't possess the enzymes needed for photorepair of thymine dimers. They're only in prokaryotes.