The correct explanation of the forces involved when a basketball bounces off the floor is:
When the ball hits the floor, the ball pushes down against the floor and the floor pushes back against the ball.
This statement highlights Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. When the basketball impacts the floor, it exerts a downward force on the floor; simultaneously, the floor exerts an equal and opposite force upward against the basketball, causing it to bounce back up.