What does the prefix "ab-" indicate?

The prefix "ab-" signifies a movement or direction away from something. In medical terminology and other scientific contexts, it is often used to denote separation or removal. For instance, "abduction" refers to the movement away from the midline of the body, while "abnormal" indicates a state that deviates away from what is typical or expected. This concept of moving away is central to the use of the prefix, which clearly aligns with the selected answer. The other options have distinct meanings that do not capture this specific sense of detachment or removal that "ab-" embodies.