An object that is moving will stop moving when a. something pushes or pulls it to a stop. b. it has stopped speeding up. c. the force that is making it move stops pushing it. d. it has used up all its momentum.

A. something pushes or pulls it to a stop

Explanation:

According to Newton's first law of motion, An object at rest or in motion will continue to be in that state unless an external force acted on it. A body at rest will continue to be in such position until a force is exerted on it .

A body in motion is moved by a particular force, the only way that body in motion  can be altered  is if it is acted upon by an unbalancing force. Example consider throwing a ball to the air. According to Newton's law the ball will always be in uniform motion unless an opposing or unbalanced force which is the gravitational force act on it .  The ball is been pulled by an unbalanced  gravitational force .

The Newton first law is also known as the law of inertia .