Which of the following refers to the meaning of "Retro-"?

The prefix "retro-" originates from Latin, meaning "back" or "backward." It is commonly used in medical terminology to describe conditions or processes that involve a movement or reversion to a previous state, location, or time.

For instance, "retrograde" refers to a backward flow or movement, often used in terms like retrograde amnesia, where one loses memories from the past. Thus, recognizing that "retro-" signifies backward movement clarifies why the answer is "backward." Each of the other choices represents a different direction or state of movement, which does not align with the established meaning of "retro-."