Step 1: Aromaticity Conditions. For a compound to be aromatic, it must satisfy Hückel's rule, which states that a molecule is aromatic if it has a planar ring structure with \( 4n + 2 \) π-electrons (where \(n\) is a non-negative integer).
Step 2: Analyze Each Compound. - (A) This compound is not aromatic because it has 6 π-electrons (a common number for aromatic systems), but the ring is not planar, so it is not aromatic. - (B) This compound has a nitrogen atom and a conjugated system, making it aromatic. - (C) This compound contains a 6-membered ring with alternating single and double bonds, fitting the requirements for aromaticity with 6 π-electrons. - (D) This compound has a conjugated system and satisfies the aromaticity condition with 6 π-electrons.
Step 3: Conclusion. Thus, the aromatic compounds are (B), (C), and (D). The correct answer is (3).
