In the following reaction :
`H_(3)C-overset(CH_(3))overset("| ")underset(CH_(3))underset("| ")"C "-CH=CH_(2)overset(H_(2)O //H^(o+))rarrA`
The major product A is :

Options

A. `underset(OH)underset("| ")(CH_(2))-underset(CH_(3))underset("| ")overset(CH_(3))overset("| ")"C "-CH_(2)-CH_(3)`
B. `H_(3)C-overset(CH_(3))overset("| ")underset(CH_(3))underset("| ")"C "-underset(OH)underset("| ")"CH"-CH_(3)`
C. `H_(3)C-overset(CH_(3))overset("| ")underset(CH_(3))underset("| ")"C "-CH_(2)-underset(OH)underset("| ")(CH_(2))`
D. `H_(3)C-overset(CH_(3))overset("| ")underset(OH)underset("| ")"C "-underset(CH_(3))underset("| ")"C "-CH_(3)`

Explanation

To determine the major product A from the given reaction, let's analyze the steps involved in the reaction mechanism.

### Step 1: Identify the Reactants
The reactant given is:
\[ \text{H}_3\text{C}-\overset{\text{CH}_3}{\underset{\text{CH}_3}{\text{C}}}-\text{CH}=\text{CH}_2 \]
This structure indicates that we have a substituted alkene with a double bond between the last two carbon atoms.

### Step 2: Protonation of the Alkene
In the presence of an acid (H⁺), the double bond can be protonated. The double bond acts as a nucleophile and can attack the proton (H⁺). There are two possible sites for protonation:
1. Protonation at the terminal carbon (C1).
2. Protonation at the internal carbon (C2).

### Step 3: Formation of Carbocations
1. **If protonation occurs at C1**:
- The structure becomes:
\[ \text{C}^+ - \text{CH}_2 - \text{CH}_3 \]
- This leads to a primary carbocation, which is less stable.

2. **If protonation occurs at C2**:
- The structure becomes:
\[ \text{C}^+-\text{CH}_3 - \text{CH}_2 - \text{CH}_3 \]
- This leads to a more stable secondary carbocation.

### Step 4: Stability of Carbocations
The stability of carbocations increases with the number of alkyl groups attached to the positively charged carbon. In this case, the secondary carbocation formed by protonation at C2 is more stable than the primary carbocation formed by protonation at C1.

### Step 5: Rearrangement of Carbocations
If possible, the carbocation can undergo rearrangement to form a more stable carbocation. In this case, the secondary carbocation can rearrange to a tertiary carbocation by migrating a methyl group from an adjacent carbon.

### Step 6: Nucleophilic Attack by Water
Once the stable carbocation is formed, water (acting as a nucleophile) can attack the positively charged carbon, leading to the formation of an alcohol.

### Step 7: Final Product Formation
After the nucleophilic attack, the final product will have the hydroxyl group (–OH) attached to the carbon where the carbocation was formed. The major product A will be:
\[ \text{CH}_3 - \text{C}(\text{OH}) - \text{CH}_3 - \text{CH}_2 - \text{CH}_3 \]

### Conclusion
The major product A is a tertiary alcohol formed from the more stable carbocation. The correct answer is option D, which corresponds to the structure of the major product.

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