Acceleration indicates how quickly what changes over time?

Acceleration is defined as the rate of change of velocity with respect to time. It measures how quickly an object's speed and/or direction of motion is changing. When an object accelerates, its velocity increases or decreases, which can be due to a change in speed, a change in direction, or both.

Velocity itself is a vector quantity that includes both the speed and the direction of an object. Therefore, when we discuss acceleration, we are specifically focusing on how the velocity of an object is altering over time—whether it speeds up, slows down, or changes direction.

The other options do not relate to the concept of acceleration in the same manner. Mass is a measure of the amount of matter in an object and does not change with time under normal circumstances. Force is related to the mass of an object and its acceleration (as defined by Newton's second law) but does not indicate a change over time by itself. Energy can change during physical processes, but it is not directly linked to the concept of how rapidly something changes with respect to time like velocity is with acceleration.