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

Explanation

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 formed by the migration of each group.

### Step-by-step Solution:

1. **Identify the Carbocation Structure**:
The carbocation has a positive charge on one of the carbon atoms, and we have two possible migrating groups: a hydrogen atom (H) and a methyl group (CH3). The carbocation can be represented as:
```
H H
| |
H3C-C- C^+ -C-CH3
| |
OH H
```

2. **Determine the Migration Possibilities**:
The groups that can migrate are:
- CH3 from C4
- H from C4
- CH3 from C2
- H from C2

3. **Evaluate Migration of CH3 from C4**:
If CH3 migrates from C4 to the positively charged carbon, the resulting carbocation will be a secondary carbocation:
```
H H
| |
H3C-C- C -C-CH3
| |
OH H
```
This secondary carbocation is less stable than a tertiary carbocation.

4. **Evaluate Migration of H from C4**:
If H migrates from C4, the resulting carbocation will be:
```
H H
| |
H3C-C- C^+ -C-CH3
| |
OH H
```
This forms a tertiary carbocation, which is more stable than the secondary carbocation formed by the migration of CH3.

5. **Evaluate Migration of CH3 from C2**:
If CH3 migrates from C2, the resulting carbocation will also be:
```
H H
| |
H3C-C^+ -C -C-CH3
| |
OH H
```
This forms a secondary carbocation, which is also less stable.

6. **Evaluate Migration of H from C2**:
If H migrates from C2, the resulting carbocation will be:
```
H H
| |
H3C-C -C^+ -C-CH3
| |
OH H
```
This results in a tertiary carbocation as well.

7. **Conclusion**:
The most stable carbocation is formed when H migrates from C4, resulting in a tertiary carbocation. Therefore, the hydrogen atom from C4 is the most likely to migrate to the positively charged carbon.

### Final Answer:
The group that is most likely to migrate to the positively charged carbon is **H from C4**.