Assertion: The process of pairing of the chromosomes is called synapsis.
Reason: Synapsis occurs during leptotene stage.

Options

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

Explanation

To analyze the assertion and reason provided in the question, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "The process of pairing of the chromosomes is called synapsis."
- This statement is true. Synapsis is indeed the process where homologous chromosomes pair up during meiosis.

2. **Understanding the Reason**:
- The reason states that "Synapsis occurs during the leptotene stage."
- This statement is false. Synapsis actually occurs during the zygotene stage of prophase I in meiosis, not during leptotene.

3. **Conclusion**:
- Since the assertion is true and the reason is false, the correct relationship between the two statements is that the assertion is true, but the reason is incorrect.

4. **Final Answer**:
- Therefore, the correct option is: "If assertion is true, the reason is false."