A : A point charge cannot exert force on itself.
R : Coulomb force is a central force.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statements, then mark (4).

Answer

To solve the assertion and reason question, we need to analyze both statements carefully.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "A point charge cannot exert force on itself."
- This is based on the principle that a force is exerted between two distinct charges. A single point charge cannot exert a force on itself because there is no second charge present to interact with.

2. **Understanding the Reason**:
- The reason states that "Coulomb force is a central force."
- This is true as Coulomb's law describes the electrostatic force between two charges as being directed along the line joining the two charges and is dependent on the distance between them. This means that the force acts along the line connecting the centers of the two charges, hence it is a central force.

3. **Evaluating the Truth of Both Statements**:
- Both the assertion and the reason are true statements.
- However, the reason does not provide a correct explanation for the assertion. The assertion is about the inability of a single charge to exert force on itself, while the reason discusses the nature of the force between two charges.

4. **Conclusion**:
- Since both statements are true but the reason does not explain the assertion correctly, the correct answer is that both the assertion and reason are true, but the reason is not the correct explanation for the assertion.

### Final Answer:
- The correct option is **B**: Both assertion and reason are true, but reason is not the correct explanation for assertion.

---