Assertion `:-` ADH prevents diuresis.
Reason `:-` ADH also affect the kidney function by its constrictory effects on blood vessels.

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

### Step-by-Step Solution:

1. **Understanding the Assertion**: The assertion states that "ADH prevents diuresis."
- **Explanation**: ADH (Antidiuretic Hormone), also known as vasopressin, is a hormone that helps the kidneys manage the amount of water in the body. When ADH is present, it promotes water reabsorption in the kidneys, thus reducing urine output (diuresis).

2. **Understanding the Reason**: The reason states that "ADH also affects kidney function by its constrictory effects on blood vessels."
- **Explanation**: ADH not only promotes water reabsorption but also has vasoconstrictive properties, meaning it can constrict blood vessels. This effect can help increase blood pressure and also influence kidney function by altering blood flow.

3. **Evaluating the Truth of Assertion and Reason**:
- Both the assertion and the reason are true. ADH does prevent diuresis and it does have effects on kidney function through its action on blood vessels.

4. **Determining the Relationship**: The next step is to determine if the reason provided correctly explains the assertion.
- **Explanation**: While both statements are true, the reason given does not directly explain why ADH prevents diuresis. The prevention of diuresis is primarily due to the reabsorption of water facilitated by ADH, rather than its effect on blood vessel constriction.

5. **Conclusion**: Based on the evaluation, we can conclude that:
- The assertion is true.
- The reason is true.
- However, the reason is not a correct explanation for the assertion.

### Final Answer:
The correct option is: "If both assertion and reason are true but the reason is not a correct explanation of the assertion."

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