..... activates the adrenal cortex to release aldosterone .

Options

A. Renin
B. Angiotensin I
C. Angiotensin II
D. ANF

Answer

To solve the question regarding which substance activates the adrenal cortex to release aldosterone, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of Aldosterone**: Aldosterone is a hormone produced by the adrenal cortex that plays a crucial role in regulating blood pressure and electrolyte balance by promoting sodium retention and potassium excretion in the kidneys.

2. **Identify the Activator of the Adrenal Cortex**: The question asks which substance activates the adrenal cortex to release aldosterone.

3. **Analyze the Options**:
- **Option 1: Tannin** - This is incorrect. Tannin is not a hormone and does not activate the adrenal cortex.
- **Option 2: Angiotensin I** - This is also incorrect. Angiotensin I is a precursor that is converted to Angiotensin II but does not directly activate the adrenal cortex.
- **Option 3: Angiotensin II** - This is correct. Angiotensin II is a potent vasoconstrictor and stimulates the adrenal cortex to release aldosterone.
- **Option 4: ANF (Atrial Natriuretic Factor)** - This is incorrect. ANF is involved in reducing blood pressure and promoting sodium excretion, but it does not activate the adrenal cortex.

4. **Conclusion**: Based on the analysis, the correct answer is **Option 3: Angiotensin II**, as it is the substance that activates the adrenal cortex to release aldosterone.

### Final Answer:
**Angiotensin II activates the adrenal cortex to release aldosterone.**

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