Assertion `:-` Angiotensin II is a powerful vasconstrictor
Reason `:-` Aldosterone causes reabsorption of `Na^(+)` and water from distal parts of the tubule.

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 "Angiotensin II is a powerful vasoconstrictor." This means that Angiotensin II causes blood vessels to constrict, which can lead to an increase in blood pressure.

2. **Understanding the Reason**: The reason provided is "Aldosterone causes reabsorption of Na⁺ and water from distal parts of the tubule." Aldosterone is a hormone that promotes the reabsorption of sodium ions (Na⁺) and water in the kidneys, which can also contribute to an increase in blood volume and blood pressure.

3. **Analyzing the Relationship**:
- Angiotensin II is produced from the conversion of angiotensinogen (inactive) to angiotensin I (also inactive) by renin, and then angiotensin I is converted to angiotensin II by the enzyme ACE (Angiotensin-Converting Enzyme).
- Angiotensin II acts on the adrenal cortex to stimulate the release of aldosterone.
- Aldosterone increases the reabsorption of sodium and water, which leads to increased blood volume and pressure.

4. **Evaluating the Truth of Each Statement**:
- The assertion is true because Angiotensin II does indeed act as a powerful vasoconstrictor.
- The reason is also true because aldosterone does cause the reabsorption of Na⁺ and water.

5. **Determining the Correct Explanation**: While both statements are true, the reason does not directly explain why Angiotensin II is a vasoconstrictor. The increase in blood pressure due to vasoconstriction is not caused by aldosterone directly but is a result of Angiotensin II's action.

6. **Conclusion**: Therefore, the correct answer is that both the assertion and reason are true, but the reason is not the correct explanation for the assertion. This corresponds to option 2.