A : For a particle moving in a straight line, its acceleration must be either parallel or antiparallel to velocity.
R : A body moving along a curved path may have constant acceleration.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are false statement, then mark (4).

Answer

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

### Step 1: Analyze the Assertion
The assertion states: "For a particle moving in a straight line, its acceleration must be either parallel or antiparallel to velocity."

- In a straight line motion, the velocity of the particle can either increase or decrease.
- If the acceleration is parallel to the velocity, the particle speeds up.
- If the acceleration is antiparallel to the velocity, the particle slows down.
- Therefore, for a particle to maintain straight-line motion, the acceleration must indeed be either parallel or antiparallel to the velocity.

**Conclusion**: The assertion is **True**.

### Step 2: Analyze the Reason
The reason states: "A body moving along a curved path may have constant acceleration."

- A body moving in a curved path is constantly changing its direction.
- Even if the speed (magnitude of velocity) remains constant, the direction of the velocity vector changes, which implies that there is a change in velocity.
- This change in velocity indicates that there is acceleration, and since the direction of the velocity is changing, the acceleration must also change.
- Therefore, it is not possible for a body moving along a curved path to have constant acceleration.

**Conclusion**: The reason is **False**.

### Step 3: Combine the Conclusions
- The assertion is true, and the reason is false.

### Final Answer
Based on the analysis:
- The correct option is **Option 3**: Assertion is true, reason is false.

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