Assertion : An object may fall with a constant velocity.
Reason : This happens when acceleration of the object is equal to acceleration due to gravity.

Options

A. Both assertion and reason are true and reason is the correct explanation of assertion.
B. Both assertion and reason are true but reason is not the correct explanations of assertion.
C. Assertion is true but reason is false.
D. Both assertion and reason is false

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "An object may fall with a constant velocity." This is indeed true. An object can fall with a constant velocity when it reaches a state known as terminal velocity. At terminal velocity, the forces acting on the object are balanced.

2. **Understanding Terminal Velocity**:
- When an object falls through a fluid (like air), it experiences two main forces: the gravitational force (weight) acting downward and the drag force acting upward. As the object accelerates downward, the drag force increases until it equals the weight of the object. At this point, the net force is zero, and the object falls at a constant velocity.

3. **Understanding the Reason**:
- The reason states that "This happens when the acceleration of the object is equal to the acceleration due to gravity." This statement is misleading. For an object to fall with a constant velocity, its acceleration must be zero, not equal to the acceleration due to gravity (which is approximately 9.81 m/s² downward).

4. **Conclusion**:
- Therefore, the assertion is true (an object can fall with constant velocity), but the reason is false (the condition for constant velocity is zero acceleration, not equal to the acceleration due to gravity).

5. **Final Answer**:
- The correct option is: Assertion is true, but the reason is false.