Among the four graphs shown in the figure, there is only one graph for which average velocity over the time interval (0, T) can vanish for a suitably chosen T. Select the graph.

1. 2.
 
3. 4.

(b) Hint: For zero velocity, the displacement of the body should be equal to zero.

Step 1: Find the graph in which the displacement is zero for a time interval.

In graph (b) for one value of displacement, there are two different points of time. Hence, for one time, the average velocity is positive and for other times is equivalent negative.
As there are opposite velocities in the interval 0 to T hence average velocity can vanish in (b). This can be seen in the figure given below

Here, OA = BT (same displacement) for two different points of time.