Which of the following can not be a chiral center?

Options

A. The `C^(+)` of a carbocation
B. The `C^(*)` of a radical
C. The carbony`1`carbon in aldehydes
D. All of these

Explanation

To determine which of the given options cannot be a chiral center, we need to understand the concept of chirality and the characteristics of chiral centers.

### Step-by-Step Solution:

1. **Definition of Chiral Center**: A chiral center (often a carbon atom) is a carbon atom that is bonded to four different substituents. This asymmetry is what gives rise to chirality, meaning that the molecule cannot be superimposed on its mirror image.

2. **Evaluate Option A - Carbocation**:
- A carbocation is a positively charged carbon atom that typically has three bonds and one empty p-orbital.
- Since it is bonded to only three substituents, it cannot be a chiral center.
- Additionally, carbocations are sp² hybridized, leading to a planar structure, which introduces a plane of symmetry.

3. **Evaluate Option B - Radical**:
- A radical is a species that has an unpaired electron.
- Similar to carbocations, radicals are also sp² hybridized and typically have three substituents.
- Therefore, they cannot be chiral centers due to the same reasons: lack of four different substituents and the planar structure.

4. **Evaluate Option C - Carbonyl Carbon in Aldehydes**:
- The carbonyl carbon in an aldehyde is also sp² hybridized and is bonded to a hydrogen atom and a carbon chain (e.g., CH₃ in CH₃CHO).
- This carbon is bonded to only three substituents (one hydrogen, one carbon chain, and the carbonyl oxygen), thus it cannot be a chiral center.

5. **Conclusion**:
- All the given options (A, B, and C) cannot be chiral centers because they do not meet the requirement of being bonded to four different substituents.

### Final Answer:
All of the options (A, B, and C) cannot be chiral centers.