The ketone shown is reduced by sodium borohydride to an achiral alcohol. Select the structure(s) shown that give a chiral alcohol when reduced with sodium borohydride.

Propanone gives propan-2-ol, which has two identical methyl groups and is achiral. Butanone gives butan-2-ol and acetophenone gives 1-phenylethanol; in each the carbinol carbon bears H, OH and two different groups, so the alcohol is chiral (formed racemic). Pentan-3-one and cyclohexanone give alcohols with two identical substituents on the carbinol carbon, which are achiral.