Assertion:In molluscs, feather-like gills are present in mantle cavity.
Reason: These gills have respiratory and excretory functions.

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 regarding the assertion and reason related to molluscs, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Assertion**:
- The assertion states that "In molluscs, feather-like gills are present in the mantle cavity."
- This is a factual statement about the anatomy of molluscs.

2. **Identify the Reason**:
- The reason states that "These gills have respiratory and excretory functions."
- This statement describes the functions of the gills found in molluscs.

3. **Evaluate the Assertion**:
- The assertion is true. Molluscs do indeed have feather-like gills located in the mantle cavity. The mantle cavity is the space between the mantle and the visceral mass, and it houses these gills.

4. **Evaluate the Reason**:
- The reason is also true. The feather-like gills in molluscs serve both respiratory functions (gas exchange) and excretory functions (removal of nitrogenous waste).

5. **Determine the Relationship**:
- While both statements are true, the reason does not explain the assertion. The assertion is about the location of the gills, while the reason discusses their functions. Therefore, the reason does not provide a direct explanation for the assertion.

6. **Conclusion**:
- Since both the assertion and the reason are true, but the reason does not explain the assertion, the correct answer is: "Both assertion and reason are true, but reason is not the correct explanation of assertion."

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

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