Which of the following describes how fast velocity is changing?

The choice that describes how fast velocity is changing is acceleration. Acceleration is defined as the rate of change of velocity of an object with respect to time. It indicates not only the increase or decrease in an object’s speed but also any change in the direction of that object's velocity. For instance, if an object is speeding up, slowing down, or moving in a circular path, it is experiencing acceleration.

Other terms listed are related to the motion but do not specifically capture the concept of changing velocity. Movement refers generally to the act of changing position. Displacement refers to the vector quantity that denotes the change in position of an object. Kinematics is the branch of mechanics that describes the motion of objects without regard to the forces that cause the motion. It encompasses concepts like velocity and acceleration but does not specifically define how velocity changes. Therefore, acceleration is the most accurate term for describing how fast velocity is changing.