Answer
a. Momenta, greatest to least: B, D, C, A
b. Impulse needed to stop the ball, greatest to least: B, D, C, A
Work Step by Step
a. The momentum is mv.
In the order ABCD, the momenta are: $$p=9 \frac{kg \cdot m}{s}$$ $$p=10.2 \frac{kg \cdot m}{s}$$ $$p=9.6 \frac{kg \cdot m}{s}$$ $$p=10 \frac{kg \cdot m}{s} $$
b. The impulse is defined as the change in momentum. The order will be identical.