Answer: Push of the ball on the earth. The reaction force is equal and opposite to the action force, according to Newton's Third Law of Motion.
Explanation: In other words, when the earth pulls the ball downward with a force, the ball pushes back on the earth with an equal and opposite force. This occurs because forces are always pairs of equal and opposite forces, known as action-reaction forces. The action force is the force that initiates the interaction, while the reaction force is the force that responds to the action force. In this case, the action force is the pull of the earth on the ball, while the reaction force is the push of the ball on the earth.