Assertion: Angiotensin II increases the glomerular blood pressure thereby GFR.
Reason: Angiotensin II activates the JG cells to release renin.

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.

Answer

To solve the question regarding the assertion and reason about angiotensin II and its effects on glomerular blood pressure and GFR (glomerular filtration rate), we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "Angiotensin II increases the glomerular blood pressure thereby GFR."
- Angiotensin II is known to cause vasoconstriction of the efferent arterioles of the glomeruli, which increases glomerular blood pressure. This increase in pressure leads to an increase in GFR.

2. **Understanding the Reason**:
- The reason states that "Angiotensin II activates the JG cells to release renin."
- This statement is incorrect. Angiotensin II does not activate the juxtaglomerular (JG) cells to release renin; rather, it is the decrease in blood pressure or blood volume that stimulates the JG cells to release renin. Renin then converts angiotensinogen to angiotensin I, which is subsequently converted to angiotensin II.

3. **Evaluating the Truth of Both Statements**:
- The assertion is true because angiotensin II does increase glomerular blood pressure and GFR.
- The reason is false because angiotensin II does not activate JG cells to release renin; it is produced as a result of renin activity.

4. **Conclusion**:
- Since the assertion is true and the reason is false, the correct answer is option three: "Assertion is true but reason is false."

### Final Answer:
The correct option is: **3. Assertion is true but reason is false.**

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