Which of the following represents a pair of enantiomers?

Options

A.
B.
C.
D.

Explanation

To determine which of the given compounds represents a pair of enantiomers, we need to understand what enantiomers are. Enantiomers are a type of stereoisomer that are non-superimposable mirror images of each other. This means that they have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of atoms.

### Step-by-Step Solution:

1. **Identify the Compounds**:
- Look at the four compounds provided in the question. Write down their structural formulas if necessary.

2. **Check for Chiral Centers**:
- A chiral center (or stereocenter) is typically a carbon atom that is bonded to four different groups. Identify if any of the compounds have chiral centers.

3. **Analyze the Spatial Arrangement**:
- For the compounds that have chiral centers, examine the arrangement of the substituents around the chiral carbon.

4. **Determine Mirror Images**:
- For each pair of compounds, check if one compound is the mirror image of the other. This can be done by visualizing or drawing the mirror image of the compound.

5. **Identify Non-Superimposable Pairs**:
- Confirm if the mirror images are non-superimposable. If they cannot be aligned perfectly on top of each other, they are enantiomers.

6. **Eliminate Homomers**:
- If two compounds have the same spatial arrangement (i.e., they are on the same side), they are not enantiomers but rather diastereomers or identical.

7. **Select the Correct Pair**:
- From the analysis, select the pair of compounds that are enantiomers.

### Conclusion:
Based on the analysis, the first and second options represent pairs of enantiomers because they have chiral centers with substituents arranged in opposite configurations.