Final answer:
If a particle moves with a constant speed, the distance-time graph will be a straight line. Hence the correct answer is option A
Step-by-step explanation:
The correct answer is (A) Straight line. If a particle moves with a constant speed, the distance-time graph will be a straight line. This is because the distance traveled by the particle is directly proportional to the time elapsed. For example, if a car is moving at a constant speed of 60 km/h, the distance it travels in 1 hour will be 60 km, in 2 hours will be 120 km, and so on.