Answer: Newton's Third Law
Explanation:
Newton's Third law states that for every action there is equal and opposite reaction. The action-reaction pair acts on different bodies. This is being tested by Jack and Jill. When Jack pushes Jill's hand, Jill moves backward. An equal amount of force acts on Jack in the opposite direction and he moves backwards too. In order to push each other, they themselves would experience equal force and would move in the opposite direction.
