Assertion:- A man standing at rest on ground. Magnitude of force exerted by man on ground is equal to weight of man.
Reason:- Earth attracts man by force mg hence by Newton's third law man also attracts earth by same force.

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

To solve the question, we need to analyze both the assertion and the reason given in the problem.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that a man standing at rest on the ground exerts a force on the ground that is equal to his weight.
- Weight (W) is defined as the force due to gravity acting on an object, which can be calculated using the formula:
\[ W = mg \]
where \( m \) is the mass of the man and \( g \) is the acceleration due to gravity.

2. **Analyzing the Situation**:
- When the man is standing still (at rest), he is not accelerating. According to Newton's first law, the net force acting on him must be zero.
- The forces acting on the man are:
- The downward gravitational force (his weight) \( mg \).
- The upward normal force (the force exerted by the ground on the man), which we can denote as \( N \).

3. **Applying Newton's Second Law**:
- Since the man is at rest, the sum of the forces acting on him must equal zero:
\[ N - mg = 0 \]
- From this equation, we can conclude that:
\[ N = mg \]
- This means the normal force \( N \) exerted by the ground on the man is equal to his weight \( mg \).

4. **Understanding the Reason**:
- The reason states that the Earth attracts the man with a force \( mg \) (his weight), and by Newton's third law, the man also attracts the Earth with the same force.
- Newton's third law states that for every action, there is an equal and opposite reaction. Therefore, if the Earth exerts a force \( mg \) on the man, the man exerts a force \( mg \) on the Earth.

5. **Conclusion**:
- Both the assertion and the reason are true.
- The assertion correctly describes the relationship between the force exerted by the man and his weight.
- The reason correctly explains this relationship using Newton's third law.

### Final Answer:
Both the assertion and the reason are true, and the reason is the correct explanation for the assertion. Therefore, the correct option is **A**.

---