Aromatic compounds are:

Options

A.
B.
C.
D.

Answer

To determine which compounds are aromatic, we need to follow certain criteria. Let's break down the steps to analyze the given compounds based on the criteria for aromaticity.

### Step-by-Step Solution:

1. **Understand the Criteria for Aromaticity**:
- The compound must follow Hückel's rule, which states that it should have \(4n + 2\) π electrons, where n is a non-negative integer (0, 1, 2, ...).
- The compound must be cyclic (form a ring).
- The compound must be planar (all atoms in the same plane).
- The compound must have complete conjugation (p-orbitals must overlap).

2. **Analyze Each Compound**:
- **Compound A**:
- It has 6 π electrons (which fits \(n=1\) in \(4n + 2\)).
- It is cyclic and planar.
- It has complete conjugation.
- **Conclusion**: Compound A is aromatic.

- **Compound B**:
- It has 6 π electrons (again fits \(n=1\)).
- It is cyclic and planar.
- The lone pair can participate in resonance, contributing to the π system.
- **Conclusion**: Compound B is aromatic.

- **Compound C**:
- It has 4 π electrons (which fits \(n=0\) in \(4n\)).
- It is cyclic but does not have complete conjugation.
- **Conclusion**: Compound C is anti-aromatic (not aromatic).

- **Compound D**:
- It has 6 π electrons (fits \(n=1\)).
- It is cyclic and planar.
- The negative charge does not participate in delocalization but does not affect the aromaticity as long as there are 6 π electrons and complete conjugation.
- **Conclusion**: Compound D is aromatic.

3. **Final Summary**:
- The aromatic compounds from the options are A, B, and D.
- Compound C is anti-aromatic.

### Final Answer:
The aromatic compounds are A, B, and D.

---