Which Occurs in a Pyrimidine, but Not in a Purine

Multiple Choice

Which occurs in a pyrimidine, but not in a purine?

A) Two nitrogens in a six-sided ring
B) A double-bonded pair of carbon atoms in a six-sided ring
C) Two carbonyl groups as part of a six-sided ring
D) An amino group bonded to a six-sided ring
E) A five-sided ring fused to a six-sided ring