Which of the following prefixes means "after" or "behind"?

The prefix that means "after" or "behind" is "post-." This prefix is derived from Latin, where "post" translates directly to "after." It is commonly used in medical terminology to indicate something that occurs later in time or position. For instance, in terms like "postoperative," it signifies the period that follows a surgical operation, while "postnatal" indicates the time after birth.

In contrast, the other prefixes denote different meanings. "Anter-" relates to "before" or "front," "trans-" suggests "across" or "through," and "ultra-" implies "beyond" or "excessive." Understanding these prefixes helps in decoding medical terms and their implications in a clinical context.