Assertion: The proton gradient is broken down due to the movement of protons across the membrane to stroma through the transmembrane channerl of the `F_(0)` of the ATPase.
Reason: The breakdonw of proton gradient leads to release of energy.

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the proton gradient is broken down due to the movement of protons across the membrane to the stroma through the transmembrane channel of the F0 component of ATPase.
- This means that protons (H⁺ ions) are moving from a higher concentration area (inside the thylakoid lumen) to a lower concentration area (the stroma) through ATP synthase.

2. **Understanding the Reason**:
- The reason given is that the breakdown of the proton gradient leads to the release of energy.
- As protons move down their concentration gradient, energy is released, which is utilized for ATP synthesis.

3. **Analyzing the Relationship**:
- The assertion is correct because the movement of protons through ATP synthase does indeed break down the proton gradient.
- The reason is also correct as the breakdown of this gradient does release energy, which is used to synthesize ATP.

4. **Evaluating the Explanation**:
- However, while both statements are correct, the reason does not directly explain the assertion. The assertion describes the process of proton movement, while the reason describes the consequence of that movement (energy release).

5. **Conclusion**:
- Therefore, the correct answer is that both the assertion and the reason are correct, but the reason is not the correct explanation for the assertion.

### Final Answer:
Both assertion and reason are correct; however, the reason is not the correct explanation for the assertion.