The reaction sequence
`C_(6)H_(5)-CH=CH-CHOoverset([X])rarr C_(6)H_(5)-CH_(2)-CH_(2)-CH_(2)OH`
[X] will be

Options

A. `LiAlH_(4)`
B. `NaBH_(4)`
C. Aluminium isopropoxide
D. All of these

Answer

To solve the problem, we need to identify the reagent [X] that can convert the unsaturated aldehyde (cinnamaldehyde) to the corresponding saturated alcohol. The reaction sequence is as follows:

**Step 1: Identify the starting material and the product.**
- Starting material: C₆H₅-CH=CH-CHO (cinnamaldehyde)
- Product: C₆H₅-CH₂-CH₂-CH₂OH (a primary alcohol)

**Step 2: Analyze the functional groups.**
- The starting material contains an aldehyde group (-CHO) and a double bond (C=CH).
- The product is a primary alcohol (-CH₂OH) with no double bonds.

**Step 3: Determine the type of reaction required.**
- We need to reduce both the double bond (C=CH) and the aldehyde group (CHO) to achieve the final product.

**Step 4: Identify suitable reducing agents.**
- Lithium aluminum hydride (LiAlH₄) is a strong reducing agent that can reduce both aldehydes and alkenes.
- Sodium borohydride (NaBH₄) is a milder reducing agent that can reduce aldehydes but not alkenes.
- Aluminum isopropoxide is not typically used as a reducing agent for these types of reactions.

**Step 5: Conclude the best reagent.**
- Since we need to reduce both the double bond and the aldehyde group, the best choice for [X] is lithium aluminum hydride (LiAlH₄).

Thus, the answer is:
**[X] = Lithium aluminum hydride (LiAlH₄)**