The answer is ultraviolet rays
Answer:
D. the masses of the objects and the distance between them
Explanation:
Gravitation is a force, a force doesn't care about the shape or density of objects, only about their masses... and distances.
And you can get it using the following equation:

Where :
G is the universal gravitational constant
: G = 6.6726 x 10-11N-m2/kg2
m represent the mass of each of the two objects
d is the distance between the centers of the objects.
Hi,
The answer is D, Gravitational.
Hope this helps.
r3t40
My guess is either they come to a stop when they come in contact, or one ball is going to go the opposite direction.