BITSAT 2018 Slot 2 Solved Paper

For the uniformly accelerated/decelerated motion,
v2=u2±2gh
So, from this equation, we can say v-h graph 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 (0→A)
When t=1, velocity reverses its direction (A′→B)