Answer:
(3) when it is caught and then thrown back
Explanation:
Since it is known that the ball has the same speed just before being caught and just after being thrown, therefore, the change in momentum is same for the case (1) when it is caught and case (2) when it is thrown.
But the change in momentum is greatest in case (3) because it is stopped and then being returned back hence twice the change in momentum as compared to case (1) and case (2).
Therefore, the greatest change in momentum is when the ball is stopped and then thrown back.
