Final answer:
The term that causes an object to change motion is force. A change in motion is essentially a change in velocity, which implies an acceleration has occurred, as per Newton's first law. So, force is the correct answer.
Step-by-step explanation:
The term that causes an object to change motion is force (F). When we talk about a change in motion, we are referring to a change in velocity, which means that an acceleration has occurred. According to Newton's first law, a nonzero net external force is needed to cause this change in motion. Hence, acceleration can occur either as a change in speed, a change in direction, or both.
Acceleration is defined as the rate at which velocity changes. It is important to understand that velocity is a vector quantity, meaning it has both magnitude and direction. Therefore, acceleration can occur due to changes in the speed of an object, its direction, or both.