Appropriate reducing agent for the following conversion is -
`CH_(2)=CH-CH_(2)-overset(O)overset(||)C-H rarr CH_(3)-CH_(@)-CH_(2)-CH_(2)OH`

Options

A. `LiAlH_(4)//H_(2)O`
B. `NaBH_(4)//H_(2)O`
C. `Na+C_(2)H_(5)OH`
D. `B_(2)H_(6)//H^(+)`

Explanation

To determine the appropriate reducing agent for the conversion of the compound `CH2=CH-CH2-C(=O)H` (an aldehyde with a carbon-carbon double bond) to `CH3-CH2-CH2-CH2OH` (a primary alcohol), we need to analyze the reaction and the reducing agents provided.

### Step-by-Step Solution:

1. **Identify the Functional Groups**:
- The starting compound has an aldehyde functional group (`-C(=O)H`) and a carbon-carbon double bond (`C=C`).
- The product is a primary alcohol (`-CH2OH`), and the carbon-carbon double bond has been reduced to a single bond.

2. **Determine the Required Reductions**:
- We need to reduce the aldehyde group to a primary alcohol.
- We also need to reduce the carbon-carbon double bond to a single bond.

3. **Evaluate the Reducing Agents**:
- **Lithium Aluminum Hydride (LiAlH4)**: A strong reducing agent that can reduce aldehydes and ketones but does not affect carbon-carbon double bonds. Therefore, it is not suitable for this reaction.
- **Sodium Borohydride (NaBH4)**: A mild reducing agent that can reduce aldehydes and ketones but not carbon-carbon double bonds. Hence, it is also not suitable.
- **Sodium in Ethanol**: This can reduce aldehydes, but it does not reduce carbon-carbon double bonds effectively. Thus, it is not the best choice.
- **Boron Trifluoride (B2H6) in presence of H+**: This reagent can reduce both aldehydes to primary alcohols and carbon-carbon double bonds to single bonds. This makes it suitable for the required transformation.

4. **Conclusion**:
- The best reducing agent for the conversion of `CH2=CH-CH2-C(=O)H` to `CH3-CH2-CH2-CH2OH` is **B2H6 in presence of H+**.

### Final Answer:
The appropriate reducing agent for the conversion is **B2H6 in presence of H+**.