In the following carbocation, `H//CH_(3)` that is most likely to migrate to the positively charged carbon is
`H_(3)overset(1)C - underset(OH)underset(|)overset(H)overset(|_(2))C -_(3) underset(H)underset(|)overset(+)C - underset(CH_(3))underset(|)overset(H)overset(|_(4))C - overset(5)CH_(3)`

Options

A. `CH_(3)" at " C -4`
B. `H " at " C-4`
C. `CH_(3)" at " C -2`
D. `H " at "C-2`

Answer

To determine which group (H or CH₃) is most likely to migrate to the positively charged carbon in the given carbocation, we need to analyze the stability of the carbocations that would form after migration.

### Step-by-Step Solution:

1. **Identify the Structure of the Carbocation**:
The given structure can be summarized as:
```
H3C - OH
|
H - C+ - CH3
|
H
```
Here, the positively charged carbon is connected to three groups: a hydroxyl group (OH), a hydrogen (H), and a methyl group (CH₃).

2. **Consider Possible Migrations**:
The groups that can migrate to the positively charged carbon are:
- The hydrogen atom from the carbon adjacent to the positively charged carbon (C2).
- The methyl group (CH₃) from the carbon adjacent to the positively charged carbon (C4).

3. **Evaluate the Stability of Resulting Carbocations**:
- **If H migrates from C2 to C3**:
- The structure will become:
```
H3C - C+ - OH
|
CH3
```
- This results in a tertiary carbocation (3°), which is highly stable due to hyperconjugation and inductive effects from the surrounding groups.

- **If CH₃ migrates from C4 to C3**:
- The structure will become:
```
H3C - OH
|
H - C+ - H
```
- This results in a secondary carbocation (2°), which is less stable compared to a tertiary carbocation.

4. **Conclusion**:
Since the tertiary carbocation formed by the migration of hydrogen is more stable than the secondary carbocation formed by the migration of the methyl group, the hydrogen atom (H) from C2 is the most likely to migrate to the positively charged carbon (C3).

### Final Answer:
The hydrogen (H) from carbon C2 is most likely to migrate to the positively charged carbon.