Which prefix is associated with the meaning "within" or "inner"?

The prefix "endo" is derived from the Greek word "endon," which translates to "within" or "inside." This prefix is commonly used in various scientific and medical terms to denote something located within a structure or system. For instance, in the term "endocrine," it refers to glands that release hormones internally into the bloodstream. Understanding this prefix is essential in fields like veterinary medicine, where it helps in accurately describing internal processes, conditions, or structures within animals.

The other prefixes, such as "exo," refer to "outside," "ecto" also means "outside" or "external," and "hyper" indicates "above" or "excessive." These meanings contrast with "endo," which emphasizes an internal or inner aspect, making "endo" the correct choice in the context of the question.