Correct Answer - A::D
Since the graph is astraight line, its slope is constant it means acceleration of the pariticle is constant. Velocity of the particle changes from positive to negative at `t=10`s so particle changes direction at this time. The particle has zero displacement up to 20 s, but not for the entire motion. The average speed in the interval of 0 to 10 s is the same as the average speed in the internal of 10 s to 20 s because distance covered in both time interval is same.
