21. Which of the following is an application of Newton's Third Law of Motion? * 1 point
A. A skydiver falls away from a plane toward the ground.
B. A truck accelerates more slowly when it is fully loaded than when it is empty.
C. A ball sits on the ground until a player kicks it. The nonzero net force sets the ball in motion.
D. A rocket can accelerate when it pushes gas backward. The reaction force pushes the rocket forward.