Cesar and Jill went to a field to play soccer. As the ball downward toward Jill, Jill used her foot to kick the ball and keep it in play. Cesar realized he could apply scientific principles to a soccer game. Which of the following best describes the scientific principle that Cesar observes as Jill kicks the ball?

A. An unbalanced force has no effect on the ball.
B. Gravity on the ball is equal to the force of friction.
C. A net force of zero changes the direction of the ball.
D. Unbalanced forces change the ball’s speed and the direction of motion.