Which of the following set of isomerism is possible simultaneously
in isomeric pair of compound ?

Options

A. chain and position isomerism
B. function and metamerism
C. position and functional isomerism
D. position and metamerism

Explanation

To solve the question regarding which set of isomerism is possible simultaneously in an isomeric pair of compounds, we will analyze the types of isomerism mentioned and determine if any can coexist in the same compound.

### Step-by-Step Solution:

1. **Understanding Isomerism**:
- Isomerism occurs when two or more compounds have the same molecular formula but differ in the arrangement of atoms or groups within the molecules.

2. **Types of Isomerism**:
- **Chain Isomerism**: Different arrangements of the carbon skeleton (e.g., straight-chain vs. branched-chain).
- **Position Isomerism**: Different positions of a functional group or substituent on the carbon chain.
- **Functional Isomerism**: Different functional groups (e.g., alcohol vs. ether).
- **Metamerism**: Different alkyl groups attached to the same polyvalent functional group.

3. **Analyzing Possible Combinations**:
- **Chain and Position Isomerism**: These can occur simultaneously. For example, you can have a branched chain with a functional group in different positions.
- **Position and Functional Isomerism**: These cannot occur simultaneously since a change in position typically involves the same functional group.
- **Metamerism and Position Isomerism**: These can occur simultaneously, especially in compounds like ketones where the position of the carbon chain can vary while maintaining the same functional group.

4. **Conclusion**:
- The only combination that can occur simultaneously in a compound is **Position Isomerism and Metamerism**. For example, in ketones, you can have different positions of the carbon chain (position isomerism) while also having different alkyl groups (metamerism).

### Final Answer:
The correct answer is that **Position Isomerism and Metamerism can occur simultaneously** in an isomeric pair of compounds.