Which of the following pair are not related as metamer`:-`

Options

A.
B.
C.
D.

Explanation

To determine which pairs are not related as metamers, we first need to understand what metamerism is. Metamers are structural isomers that have the same molecular formula but differ in the arrangement of carbon atoms or alkyl groups around a functional group.

### Step-by-Step Solution:

1. **Identify the Functional Groups**:
- Look at the functional groups in each pair of compounds provided in the options.

2. **Analyze Each Option**:
- **Option 1**:
- Compound A: CH3CH2C(=O)CH2CH3 (a ketone)
- Compound B: CH3CH(CH3)C(=O)CH3 (a ketone)
- Both compounds have the same functional group (ketone) and differ in the carbon arrangement. Thus, they are metamers.

- **Option 2**:
- Compound A: C6H5OCH2CH3 (an ester)
- Compound B: C6H5O(C6H11) (an ester)
- Both compounds have the same functional group (ester) and differ in the alkyl groups. Thus, they are metamers.

- **Option 3**:
- Compound A: C6H5NH(CH3) (an amine)
- Compound B: C6H5NH(C6H5) (an amine)
- Both compounds have the same functional group (amine) and the same structure, differing only in the substituents. Thus, they are not metamers.

- **Option 4**:
- Compound A: C6H5NH(CH3) (an amine)
- Compound B: C6H5NH(C6H11) (an amine)
- Both compounds have the same functional group (amine) and differ in the alkyl groups. Thus, they are metamers.

3. **Conclusion**:
- After analyzing all options, the pair that is not related as metamers is **Option 3**.

### Final Answer:
**Option 3** is the correct answer as they are not metamers of each other.

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