Which of the following structures is chiral?

Options

A.
B.
C.
D.

Explanation

To determine which of the given structures is chiral, we need to analyze each option based on the criteria for chirality. A compound is considered chiral if it does not have any plane of symmetry or center of symmetry.

### Step-by-Step Solution:

1. **Understanding Chirality**:
- A chiral compound lacks any plane of symmetry and center of symmetry. This means that if you were to divide the molecule in half, the two halves would not be mirror images of each other.

2. **Analyzing Option A**:
- The first structure is a cyclobutane ring with two chlorines and two bromines.
- If we draw a line through the center of the ring, we can see that one bromine can be reflected by the other bromine, indicating a plane of symmetry.
- **Conclusion**: This structure is not chiral.

3. **Analyzing Option B**:
- The second structure also features a cyclobutane ring with two chlorines and two bromines.
- Here, we can find a center of symmetry as one bromine reflects the other bromine and one chlorine reflects the other chlorine.
- **Conclusion**: This structure is not chiral.

4. **Analyzing Option C**:
- The third structure presents another cyclobutane ring with the same arrangement of two bromines and two chlorines.
- Similar to the previous options, we can identify multiple planes of symmetry in this structure.
- **Conclusion**: This structure is not chiral.

5. **Analyzing Option D**:
- The fourth structure consists of a cyclobutane ring with two bromines and two chlorines.
- In this case, there are no planes of symmetry or centers of symmetry present. The arrangement of substituents does not allow for any reflection or division that results in identical halves.
- **Conclusion**: This structure is chiral.

6. **Final Answer**:
- The chiral compound is **Option D**.