Which of the Following Correctly Describes the Core Ring System

Which of the following correctly describes the core ring system found in barbituric acid and all barbiturates?

A) an aromatic ring which has three carbon atoms and three nitrogen atoms
B) an aromatic ring which has four carbon atoms and two nitrogen atoms
C) a non-aromatic ring which has three carbon atoms and three nitrogen atoms
D) a non-aromatic ring which has four carbon atoms and two nitrogen atoms