Assertion: If net force on a body zero, it is either at rest or moving with a constant linear velocity. Nothing else can happen.
Reason: Constant velocity means linear acceleration is zero

Options

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

Explanation

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

### Step 1: Analyze the Assertion
The assertion states: "If net force on a body is zero, it is either at rest or moving with a constant linear velocity. Nothing else can happen."

- According to Newton's First Law of Motion, if the net force acting on an object is zero, the object will remain at rest or continue to move at a constant velocity. This part of the assertion is true.
- However, the phrase "nothing else can happen" is misleading. While the object may be at rest or moving with constant velocity, it does not account for rotational motion. An object can have zero net force but still be experiencing a net torque, leading to rotational motion. Therefore, this part of the assertion is false.

### Step 2: Analyze the Reason
The reason states: "Constant velocity means linear acceleration is zero."

- Linear acceleration is defined as the rate of change of velocity with respect to time. If an object is moving with constant velocity, then its velocity is not changing over time. Thus, the change in velocity (dv) is zero, leading to zero acceleration (a = dv/dt = 0). This part of the reason is true.

### Conclusion
- The assertion is false because it incorrectly states that nothing else can happen besides being at rest or moving with constant velocity when the net force is zero.
- The reason is true because constant velocity indeed implies zero linear acceleration.

### Final Answer
The correct option is: Assertion is false, but the reason is true.

---