When the achiral dione shown (below left) was incubated in water with baker’s yeast, reduc...

When the achiral dione shown (below left) was incubated in water with baker’s yeast, reduction of one of the C=O groups occurred to give a single stereoisomer of the product. This product corresponded to hydrogen transfer to the Re face of the pro-R carbonyl group. Which product is this?

A.

B.

C.

D.