Assertion : Pharyngeal nephridia play a role in the conservation of water in the earthworm.
Reason : They help the earthworm in keeping the skin moist for cutaneous respiration.

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 analyze the given assertion and reason, let's break down the information step by step:

### Step 1: Understand the Assertion
- **Assertion**: Pharyngeal nephridia play a role in the conservation of water in the earthworm.
- **Explanation**: Pharyngeal nephridia are specialized excretory structures found in earthworms. They are involved in an enteronephric condition, which means they excrete waste products into the gut rather than directly into the environment. This adaptation helps in conserving water by reabsorbing water from the excretory products before they are eliminated.

### Step 2: Understand the Reason
- **Reason**: They help the earthworm in keeping the skin moist for cutaneous respiration.
- **Explanation**: Cutaneous respiration refers to the process of gas exchange through the skin. For this to occur efficiently, the skin must remain moist. However, the pharyngeal nephridia do not directly contribute to keeping the skin moist; instead, this function is performed by integumentary nephridia, which discharge waste directly to the outside environment, maintaining skin moisture.

### Step 3: Evaluate the Assertion and Reason
- The assertion is correct because pharyngeal nephridia do play a role in water conservation through their enteronephric function.
- The reason is incorrect because it attributes the function of keeping the skin moist to pharyngeal nephridia, whereas this is the role of integumentary nephridia.

### Conclusion
- Since the assertion is true and the reason is false, the correct conclusion is that the assertion is true, but the reason is false.

### Final Answer
- The correct option is: Assertion is true, but Reason is false.

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