Assertion : When we rub a glass rod with silk, the rod gets positively charged and the silk gets negatively charged.
Reason : On rubbing, electrons from silk cloth move to the glass rod.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that when a glass rod is rubbed with silk, the glass rod becomes positively charged, and the silk becomes negatively charged.
- This is a well-known phenomenon in electrostatics where materials acquire opposite charges when rubbed together.

2. **Understanding the Reason**:
- The reason given is that electrons from the silk cloth move to the glass rod.
- To understand this, we need to know the behavior of electrons during the rubbing process.

3. **Analyzing the Rubbing Process**:
- When the glass rod is rubbed with silk, it is actually the electrons from the glass rod that move to the silk cloth.
- As a result, the glass rod loses electrons, leading to a positive charge, while the silk cloth gains those electrons, resulting in a negative charge.

4. **Conclusion**:
- The assertion is true because the glass rod does become positively charged and the silk negatively charged.
- The reason is false because it incorrectly states that electrons move from the silk to the glass rod, when in fact, they move from the glass rod to the silk.

5. **Final Answer**:
- Therefore, the assertion is true, and the reason is false. The correct answer is that the assertion is true, but the reason is false.