Solution

d

Taking into account the physical meaning of the area under the graph of velocity versus time, we obtain the graphs of the dependence of the coordinate on time.

In case $b$), in equal time intervals, the body travels forward and backward the same distance. Consequently, for a large time, the displacement will be close to zero and the average velocity will be zero.

$$v_{av} = 0 \text{ m/s}$$

In case $c$) for equal time intervals, the body is no longer travelling equal distances. For every 4 seconds, it moves in the positive direction by 4 meters.

Here we go:

$$v_{av} = 1 \text{ m/s}$$