Which is the most suitable reagent for the following conversion ?
`CH_(3)-CH=CH-CH_(2)-overset(O)overset(||)C-CH_(3)toCH_(3)-CH=CH-CH_(2)-overset(O)overset(||)C-OH`

Options

A. Tollens' reagent
B. Benzoyl peroxide
C. `I_(2)` and NaOH solution
D. Sn and NaOH solution

Explanation

To convert the compound \( CH_3-CH=CH-CH_2-C(=O)-CH_3 \) (a ketone) into \( CH_3-CH=CH-CH_2-C(=O)-OH \) (a carboxylic acid), we need to identify the most suitable reagent for this transformation.

### Step-by-Step Solution:

1. **Identify the Functional Groups**:
- The starting compound is a ketone (specifically, 4-penten-2-one).
- The target compound is a carboxylic acid (specifically, 4-pentenoic acid).

2. **Recognize the Reaction Type**:
- The conversion involves the oxidation of a ketone to a carboxylic acid.

3. **Select the Suitable Reagent**:
- Common reagents for oxidizing ketones to carboxylic acids include strong oxidizing agents. However, in this case, we can utilize the iodoform test, which is specific for methyl ketones.
- The reagent \( I_2 \) (iodine) in the presence of \( NaOH \) (sodium hydroxide) is suitable for this transformation. This is because it can convert the methyl ketone into a carboxylic acid while also producing iodoform (\( CHI_3 \)) as a byproduct.

4. **Reaction Mechanism**:
- When the ketone reacts with \( I_2 \) and \( NaOH \), the methyl group adjacent to the carbonyl is oxidized and cleaved off, leading to the formation of the carboxylate ion \( CH_2COO^- \) and iodoform \( CHI_3 \).
- The carboxylate ion can then be protonated by adding water or an acid to yield the final carboxylic acid product.

5. **Final Product**:
- The final product after the reaction is \( CH_3-CH=CH-CH_2-C(=O)-OH \), which is the desired carboxylic acid.

### Conclusion:
The most suitable reagent for the conversion of \( CH_3-CH=CH-CH_2-C(=O)-CH_3 \) to \( CH_3-CH=CH-CH_2-C(=O)-OH \) is \( I_2 \) in the presence of \( NaOH \).