The question asks for the metamer of a given compound $(X)$, but the crucial information is missing:

1. The structure/name/formula of compound $(X)$ is not provided.
2. The option structures for A, B, C, and D are also blank.

Without these, the answer cannot be determined from chemistry principles alone.

Step 1: What is metamerism?

Metamers are compounds that have:

• the same molecular formula,
• the same functional group,
• but different alkyl groups on either side of a polyvalent atom or functional group such as $-O-$, $-NH-$, $-S-$, etc.

For example, in ethers: $\mathrm{C_4H_{10}O}$ can give metamers like:

• $\mathrm{CH_3-O-C_3H_7}$
• $\mathrm{C_2H_5-O-C_2H_5}$

Step 2: Why this question cannot be solved as given

To identify the metamer, we must compare the given compound $(X)$ with the options and check:

• same molecular formula,
• same functional group,
• different distribution of carbon chains.

But here, neither $(X)$ nor the options are visible.

Step 3: Comparison with stored answer

The stored correct answer is C, but since the actual structures are missing, I cannot independently verify that option C is correct.

So, based only on the information shown, the problem is underdetermined.