Which of the following is the best description for acceleration?

Acceleration is best described as the rate of change of velocity. This definition captures the essence of acceleration because velocity itself is defined as the speed of an object in a given direction. When an object accelerates, it may change its speed (either increasing or decreasing) or change its direction of travel, or both.

The key aspect of acceleration is that it provides a measure of how quickly the velocity of an object changes over time. This measurement is critical in understanding motion, as it allows for the analysis of how quickly an object is speeding up or slowing down in response to forces acting upon it.

In contrast, the other options do not accurately represent the concept of acceleration. For instance, an increase in speed refers solely to a specific scenario of acceleration, while distance per time relates to speed, not the change in velocity. The change in position of an object describes displacement, another important concept in motion, but it does not encompass the broader definition of acceleration.