The compound which may exhibit tautomerism:

Options

A.
B.
C.
D. All of these

Explanation

To determine which compound may exhibit tautomerism, we need to understand the concept of tautomerism itself. Tautomerism is a type of isomerism where two or more structural isomers (tautomers) can interconvert, typically involving the migration of a hydrogen atom and a change in the bonding of a double bond. The most common example of tautomerism is the keto-enol tautomerism, where a keto form (with a carbonyl group, C=O) can convert to an enol form (with a hydroxyl group, C=C-OH).

### Step-by-Step Solution:

1. **Identify the Functional Groups**:
- Look for compounds that contain a carbonyl group (C=O) and an adjacent hydrogen atom (acidic hydrogen) on the alpha carbon. This is crucial for tautomerism to occur.

2. **Check for Alpha Hydrogen**:
- Ensure that the compound has an alpha hydrogen. The presence of an acidic hydrogen on the carbon adjacent to the carbonyl carbon is necessary for the tautomeric shift.

3. **Draw the Structures**:
- For each compound, draw the keto form (with the carbonyl) and the enol form (with the hydroxyl). This will help visualize the interconversion.

4. **Analyze the Stability**:
- Consider the stability of the keto and enol forms. Generally, the keto form is more stable than the enol form, but the presence of conjugation or other stabilizing factors can influence this.

5. **Determine Tautomerism**:
- If a compound can interconvert between its keto and enol forms due to the presence of an acidic hydrogen and a carbonyl group, then it exhibits tautomerism.

6. **Evaluate Each Option**:
- Go through the provided options and apply the above criteria to determine which compound(s) exhibit tautomerism.

### Conclusion:
After analyzing the compounds based on the steps above, we can conclude that the compounds that contain a carbonyl group adjacent to an acidic hydrogen can exhibit tautomerism.