What does the prefix "endo-" denote?

The prefix "endo-" is derived from the Greek word "endon," which means "within" or "inside." It is commonly used in various scientific and medical terminologies to indicate something that occurs internally. For instance, "endoscopy" refers to the examination of the interior of a bodily organ or space using instruments. Therefore, the correct choice accurately reflects the meaning of the prefix. Understanding such prefixes is crucial in fields like medicine, biology, and related sciences, where precise language is essential for conveying accurate information.