When you bounce a basketball on the floor, the primary forces at play involve the interaction between the ball and the floor. The correct explanation is:
When the ball hits the floor, the ball pushes down against the floor and the floor pushes back against the ball.
This explanation highlights Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. When the basketball makes contact with the floor, it exerts a downward force on the floor, and simultaneously, the floor exerts an equal upward force on the ball, causing it to bounce back up.