Final answer:
A ball is shot vertically upward from a spring. This is an example of projectile motion.
Step-by-step explanation:
The correct answer is D) A spring.
A ball is shot vertically upward from a spring. When a spring is compressed and then released, it exerts a force on the ball, propelling it upward. This is an example of projectile motion, where an object is launched at an angle or vertically into the air. When a ball is shot vertically upward from a spring, it will reach its maximum height and then fall back down to the ground due to the force of gravity.