In the given reaction sequence
`Ph-CH_(2)-CHO overset(NaOH)to overset(Delta)to overset(H_(2)//Ni)to`(X)
Product (X) will be

Options

A. `{:(Ph-CH_(2)-CH-CH-Ph),(" | |"),(" OH CHO"):}`
B. `{:(Ph-CH_(2)-CH_(2)-CH-Ph),(" |"),(" "CH_(2)OH):}`
C. `{:(Ph-CH_(2)-CH_(2)-CH-Ph),(" |"),(" CHO"):}`
D. `{:(Ph-CH_(2)-CH_(2)-CH-Ph),(" |"),(" "CH_(3)):}`

Explanation

To solve the problem, we will break down the reaction sequence step by step.

### Step 1: Identify the starting compound
The starting compound is benzaldehyde (Ph-CH₂-CHO). This compound contains an aldehyde functional group.

### Step 2: Aldol Condensation Reaction
The first step involves treating the starting compound with sodium hydroxide (NaOH) and heating it. This indicates that an aldol condensation reaction will occur.

1. **Formation of Enolate Ion**: The base (NaOH) abstracts an alpha hydrogen from the benzyl group (Ph-CH₂-), forming an enolate ion.

\[ \text{Ph-CH}_2\text{-CHO} + \text{NaOH} \rightarrow \text{Ph-CH}^- \text{-CHO} + \text{H}_2\text{O} \]

2. **Nucleophilic Attack**: The enolate ion then acts as a nucleophile and attacks the carbonyl carbon of another molecule of benzaldehyde, leading to the formation of a β-hydroxy aldehyde.

\[ \text{Ph-CH}^- \text{-CHO} + \text{Ph-CHO} \rightarrow \text{Ph-CH(OH)-CH}_2\text{CHO} \]

### Step 3: Dehydration
Upon heating, the β-hydroxy aldehyde undergoes dehydration (loss of water) to form an α,β-unsaturated aldehyde.

\[ \text{Ph-CH(OH)-CH}_2\text{CHO} \overset{\Delta}{\rightarrow} \text{Ph-CH=CH-CHO} + \text{H}_2\text{O} \]

### Step 4: Reduction
The next step involves reducing the α,β-unsaturated aldehyde using hydrogen gas (H₂) in the presence of a nickel catalyst (Ni). This reduction will convert the double bond into a single bond and the aldehyde group into an alcohol.

\[ \text{Ph-CH=CH-CHO} + \text{H}_2 \xrightarrow{\text{Ni}} \text{Ph-CH}_2\text{-CH}_2\text{-CHO} \]

### Step 5: Final Product
The final product (X) after reduction is a primary alcohol, specifically benzyl alcohol (Ph-CH₂-CH₂-OH).

### Final Answer
Thus, the product (X) will be:
\[ \text{Ph-CH}_2\text{-CH}_2\text{-OH} \]