In the given reaction
`CH_(3)-overset(O)overset(||)(C)-C_(2)H_(5)overset(X)rarrCH_(3)-CH_(2)-C_(2)H_(5)`
'X' will be

Options

A. `LiAIH_(4)`
B. `NaBH_(4)`
C. `BCl_(3)SnH`
D. `NH_(2)-NH_(2)//OH^(-)`, glycol

Answer

To solve the problem, we need to identify the reagent 'X' that converts the compound \( CH_3C(=O)C_2H_5 \) (a ketone) into \( CH_3CH_2C_2H_5 \) (an alkane).

### Step-by-Step Solution:

1. **Identify the Reactant and Product**:
- The reactant is \( CH_3C(=O)C_2H_5 \), which is a ketone (specifically, 3-pentanone).
- The product is \( CH_3CH_2C_2H_5 \), which is an alkane (specifically, pentane).

2. **Understand the Reaction Type**:
- The transformation from a ketone to an alkane indicates a reduction reaction. In organic chemistry, this type of reaction typically involves the removal of the carbonyl group (C=O) and the addition of hydrogen.

3. **Evaluate the Given Options**:
- Option 1: LiAlH4 - This is a strong reducing agent that can convert ketones to alcohols, not directly to alkanes.
- Option 2: NaBH4 - Similar to LiAlH4, this is also a reducing agent that converts ketones to alcohols.
- Option 3: BCl3/SnH - This is not commonly used for reducing ketones to alkanes.
- Option 4: \( NH_2NH_2 \) in presence of \( OH^- \) and glycol - This is known as the Wolff-Kishner reduction, which specifically reduces ketones to alkanes.

4. **Conclusion**:
- The correct reagent 'X' that will convert the ketone \( CH_3C(=O)C_2H_5 \) to the alkane \( CH_3CH_2C_2H_5 \) is \( NH_2NH_2 \) (hydrazine) in the presence of \( OH^- \) and glycol.

### Final Answer:
- \( X \) will be \( NH_2NH_2 \) in presence of \( OH^- \) and glycol.