Which of the following compounds is achiral?

Options

A.
B.
C.
D.

Explanation

To determine which of the given compounds is achiral, we need to analyze each compound for the presence of a plane of symmetry. A compound is considered achiral if it has a plane of symmetry, meaning that one half of the molecule is a mirror image of the other half.

### Step-by-Step Solution:

1. **Identify the Compounds**: We have four compounds labeled A, B, C, and D. We need to examine each one to check for chirality.

2. **Analyze Compound A**:
- Compound A has an OH group on a wedge and an H on a hash, along with a trans alkyne.
- Since all four groups attached to the chiral center are different, there is no plane of symmetry present.
- **Conclusion**: Compound A is chiral.

3. **Analyze Compound B**:
- Compound B also has an OH group on a wedge and an H on a hash, along with another structure.
- Similar to Compound A, there are no two groups that reflect each other through any plane.
- **Conclusion**: Compound B is chiral.

4. **Analyze Compound C**:
- Compound C consists of an alkyne, an OH group on a wedge, and an H on a hash.
- Again, all four groups attached to the chiral center are different, indicating no plane of symmetry.
- **Conclusion**: Compound C is chiral.

5. **Analyze Compound D**:
- Compound D has an alkyne, an OH group on a wedge, and an H on a hash.
- When we examine this compound, we find that it contains a plane of symmetry. The plane can be drawn such that it bisects the molecule, reflecting the two groups on either side.
- **Conclusion**: Compound D is achiral.

6. **Final Answer**: Based on the analysis, the compound that is achiral is **Compound D**.