Answer: catching the ball is a better choice.
Explanation:
The collision of 2 objects involves involves large impact force since the force is inversely proportional to the time in which the momentum of the object changes.
Mathematically

If we catch the ball we increase the time in which the momentum of the ball is decreased thus the impact force that acts on us is lower as larger time is allowed for the ball to decrease it's momentum.
If we allow the ball to hit us the momentum of the ball changes in a short period of time thus applying a large impact force on our body thus increasing the chances of toppling.
I would say it’s “B” for the reason that the student did not experiment with a short ramp and large ball as well as a large ramp and a short ball. They have to do those experiments as well before drawing their conclusion.
Answer:
0.02 s
Explanation:
Take the (+x) direction to be up.
The average velocity v during a time interval Δt is the displacement Δx divided by Δt.
v=Δx/Δt
=x_f-x_i/t_f-t_i (1)
We assume that your height is 1.6m
Solving [1]
Δt=Δx/v
= 0.02 s