(a, c, d) As per the diagram, at point the graph is parallel to time axis hence, . As

the starting point is A hence, we can say that the particle is starting from rest. At C, the graph changes slope, hence, velocity also changes. As graph at is almost parallel to time axis hence, we can say that velocity vanishes.
At the direction of velocity changes from +ve to -ve, therefore acceleration is negative.
From the graph it is clear that
|slope at slope at
Hence, speed at will be more than at .