A ball is dropped vertically from a height d above the ground. It...

For the uniformly accelerated/decelcrated motion,

$v^{2} = u^{2} \pm 2gh$

So. from this equation. we can say~$v - h$~paragraph is parabola.

Initially, velocity is downwards $( - ve )$~after collision, it reverses the direction with smaller magnitude and velocity is upwards $( - ve )$.

So. graph (a) satisfies these conditions.

Also, When $t = 0, h = d$~Velocity increases downwards $( U \to A )$

When $t - 1$ velocity reverses its direction \left(A^{'} \to B\right)$