Assertion : An object may have varying speed without having varying velocity.
Reason : If the velocity is zero at an instant, the acceleration may not be zero at that instant.

Options

A. If both Assertion and Reason are correct and Reason is the correct explanation of assertion.
B. If both Assertion and Reason are correct but Reason in not the correct explanation of Assertion.
C. If Assertion is true but Reason is false.
D. If Assertion is false but Reason is true.

Explanation

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

### Step 1: Understand the Assertion
The assertion states: "An object may have varying speed without having varying velocity."

- **Speed** is a scalar quantity that refers to how fast an object is moving, regardless of its direction.
- **Velocity** is a vector quantity that refers to the speed of an object in a specific direction.

**Analysis of the Assertion:**
- For an object to have varying speed, it can change its speed while moving in a constant direction.
- However, if the speed is changing, the magnitude of the velocity is also changing, which means the velocity is varying as well.

Thus, the assertion is **incorrect**.

### Step 2: Understand the Reason
The reason states: "If the velocity is zero at an instant, the acceleration may not be zero at that instant."

**Analysis of the Reason:**
- Acceleration is the rate of change of velocity. It is possible for an object to have zero velocity while still experiencing acceleration.
- A classic example is an object thrown upwards. At the highest point of its trajectory, its velocity is zero, but it is still under the influence of gravitational acceleration (which is approximately 9.81 m/s² downwards).

Thus, the reason is **correct**.

### Step 3: Conclusion
Since the assertion is incorrect and the reason is correct, the overall statement is false.

### Final Answer:
- Assertion: Incorrect
- Reason: Correct