In the given reaction,
`OHC-(CH_(2))_(3)-overset(O)overset(||)C-CH_(3)overset(overset(Theta)(O)H//Delta)rarr (X)'`
the major product 'X' will be

Options

A.
B.
C.
D.

Answer

To solve the problem, we need to analyze the reaction step by step. The reaction involves an aldehyde and a ketone, and under the influence of a base and heat, it leads to the formation of a product through an intramolecular aldol condensation.

### Step-by-Step Solution:

1. **Identify the Reactants**:
The reactant structure is given as `OHC-(CH2)3-C(=O)-CH3`. This indicates that we have an aldehyde (CHO) at one end and a ketone (C=O) at the other end, with a three-carbon chain in between.

2. **Recognize the Functional Groups**:
The aldehyde group (CHO) and the ketone group (C=O) are both carbonyl groups. The carbon adjacent to the carbonyl group (the alpha carbon) has alpha hydrogens that can be removed by a base.

3. **Base-Induced Deprotonation**:
When a base is added, it will deprotonate one of the alpha hydrogens adjacent to the carbonyl group. In this case, we can remove one of the alpha hydrogens from the carbon chain (the CH2 group next to the ketone).

4. **Formation of the Nucleophile**:
After deprotonation, we will have a negatively charged nucleophile (CH2^-). This nucleophile will then attack the carbonyl carbon of the aldehyde.

5. **Nucleophilic Attack**:
The nucleophile (CH2^-) attacks the carbonyl carbon of the aldehyde. This forms a six-membered cyclic intermediate (a tetrahedral intermediate) as the nucleophile adds to the carbonyl carbon.

6. **Formation of the Aldol Product**:
The six-membered ring is formed by the nucleophilic attack. The structure now has a hydroxyl group (OH) and a ketone group (C=O) in the same molecule.

7. **Dehydration Step**:
Upon heating, the hydroxyl group (OH) can be eliminated along with a hydrogen atom from the adjacent carbon, leading to the formation of a double bond (C=C). This dehydration step results in the formation of an α,β-unsaturated carbonyl compound.

8. **Final Product**:
The final product after dehydration will be a compound with a double bond between the alpha and beta carbons relative to the carbonyl group.

### Conclusion:
The major product 'X' formed from the reaction is an α,β-unsaturated carbonyl compound.