Mass - the answer is mass. Since I need to write a bit more, the answers are not density, weight, gravity, size or anything like that!
As soon as I see "Which...", I know that the last part of the question is the list of answer choices, but you decided not to let us see them.
The answer is: A 33-Newton force pointing upward.
Answer:

Explanation:
Speed experimented by the ball before and after collision are determined by using Principle of Energy Conservation:
Before collision:


After collision:


The magnitude of the impulse delivered to the ball by the floor is calculated by the Impulse Theorem:
![Imp = (0.32\,kg)\cdot [(17.153\,\frac{m}{s} )-(-19.304\,\frac{m}{s} )]](https://tex.z-dn.net/?f=Imp%20%3D%20%280.32%5C%2Ckg%29%5Ccdot%20%5B%2817.153%5C%2C%5Cfrac%7Bm%7D%7Bs%7D%20%29-%28-19.304%5C%2C%5Cfrac%7Bm%7D%7Bs%7D%20%29%5D)

C. Forces are always in pairs
7 2 3 5 8 1 6 4 here it is