Answer: D. force applied to the foot by the ball.
Explanation:
The basic premise of force is that for every action, there is a reaction. The reaction force is the force that pushes back so to speak, against the action that you initiated.
This reaction force by acting against us, ensures that we move forward by pushing us.
When the player struck the ball, the ball pushed back against the player and this force that was applied to the foot by the ball was the reaction force.
