(A) is subjected to reduction with `Zn-(Hg//HCl)` and the product formed is N-methylmethanamine. (A) can be.

Options

A. Ethane nitrile
B. Nitroethane
C. Carbylaminoethane
D. carbylaminomethane

Explanation

To solve the problem, we need to identify compound (A) that, when subjected to reduction with Zn-Hg in the presence of HCl, yields N-methylmethanamine.

### Step-by-Step Solution:

1. **Understanding the Reaction**: The reduction process mentioned involves a Clemenson reduction, which typically reduces carbonyl compounds to alkanes or amines. In this case, we are looking for a compound that can be reduced to yield N-methylmethanamine.

2. **Identifying the Product**: The product given is N-methylmethanamine. This compound has the structure:
\[ \text{H}_2\text{N}-\text{C}(\text{CH}_3)-\text{H} \]
This indicates that the compound (A) must contain a functional group that can be converted into an amine.

3. **Considering Possible Functional Groups**: The Clemenson reduction can reduce nitriles (R-C≡N) to primary amines (R-CH2-NH2). Given that the product is a simple amine, we can infer that (A) could be a nitrile.

4. **Determining the Structure of (A)**: To yield N-methylmethanamine, (A) must be a methyl isocyanide (or isonitrile), which has the structure:
\[ \text{CH}_3-\text{C} \equiv \text{N} \]
This is because isonitriles can be reduced to amines through the Clemenson reduction.

5. **Finalizing the Answer**: Therefore, the compound (A) that can be reduced to N-methylmethanamine is methyl isocyanide, also known as carboyl amino methane.

### Conclusion:
Thus, the answer to the question is that (A) can be methyl isocyanide (carboyl amino methane).

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