Assertion : Angular momentum of sun and planet system about any point remains constant
Reason : Two equal and opposite forces will acts on them. Net torque of these two set of forces about any point is zero.

Options

A. If both Assertion and Reason are correct 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 fasle
D. If Assertion is false but Reason is true

Answer

To solve the question, we need to analyze the assertion and the reason provided and determine their validity.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that the angular momentum of the Sun and planet system about any point remains constant.
- Angular momentum (L) is conserved in a system if there is no net external torque acting on it.

2. **Analyzing the Reason**:
- The reason states that two equal and opposite forces act on the Sun and the planet (Earth), resulting in a net torque of zero about any point.
- In a gravitational system like the Sun and Earth, the gravitational force is indeed equal and opposite on both bodies (Newton's Third Law).

3. **Net Torque Calculation**:
- The net torque (τ) about any point due to these forces can be calculated as τ = r × F, where r is the position vector from the point to the line of action of the force, and F is the force.
- Since the forces are equal and opposite, and they act along the line connecting the two bodies, the torque they produce about the center of mass (or any point) cancels out, leading to a net torque of zero.

4. **Conclusion on Angular Momentum**:
- Since the net external torque is zero, the angular momentum of the Sun-planet system is conserved.
- Therefore, the assertion is correct: the angular momentum of the Sun and planet system about any point remains constant.

5. **Final Verification**:
- Both the assertion and the reason are correct, and the reason correctly explains why the assertion holds true.

### Final Answer:
Both the assertion and the reason are correct, and the reason is the correct explanation of the assertion.

---