The variation of quantity A with quantity B, plotted in Fig. 3.2 describes the motion of a particle in a straight line.

Option (a) is clearly correct as Quantity B represents time.

Option (b) is incorrect because a velocity – time graph with a positive slope does not represent uniform motion.

Option (c) is correct because if Quantity A represents displacement, the motion is uniform because the object is moving with constant velocity (slope of displacement - time graph).

Option (d) is correct because the slope of the graph is same/constant, which in case of a velocity-time graph gives that acceleration (=slope of a velocity time graph) is uniform/constant.