Assertion :- Radulla is a masticatory and nutritive structure.
Reason :- It is calcareous in nature.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are false.

Answer

To solve the question regarding the assertion and reason about the radula, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Radula is a masticatory and nutritive structure."
- The radula is indeed a structure found in molluscs that is used for feeding. It functions like a tongue with tiny teeth and helps in scraping food.

2. **Evaluating the Reason**:
- The reason states that "It is calcareous in nature."
- The radula is not calcareous; rather, it is made of chitin and proteins. Therefore, this statement is incorrect.

3. **Determining the Truth of Each Statement**:
- Since the assertion is true (the radula is a masticatory and nutritive structure), but the reason is false (the radula is not calcareous), we can conclude the following:
- Assertion: True
- Reason: False

4. **Analyzing the Options**:
- Based on the truth values of the assertion and reason, we can evaluate the provided options:
- Option 1: Both assertion and reason are true and reason is the correct explanation of assertion. (False)
- Option 2: Both assertion and reason are true but reason is not a correct explanation of assertion. (False)
- Option 3: Assertion is true but reason is false. (True)
- Option 4: Both assertion and reason are false. (False)

5. **Conclusion**:
- The correct answer is Option 3: "Assertion is true but reason is false."