Answer:
You are correct, it is (3) the ball is in motion as it rolls down the slope.
Explanation:
For number 1 it would make sense because how would the student be in motion if he is just standing there throwing the ball down the slope, not himself.
For number 2 still wouldn't make so much sense since we are talking about the ball being in motion not the student.
For number 3 it seems the most reasonable because the ball is in motion as it is rolling down the slope.
For number 4 it doesn't make sense for a ball to lose its shape just by rolling, also even if you're like: "oh, but what if its leaking air or has a hole??" well easy then. It STILL wouldn't matter because in the sentence it never specifies it has a "hole" or is "leaking air" therefore this answer is wrong.
YOUR ANSWER IS number 3.
