Which prefix suggests a position inside?

The prefix "endo-" indicates a position inside or within something. It is derived from the Greek word "endon," meaning "within" or "inner." In medical terminology, this prefix is commonly used to describe structures, processes, or conditions that occur inside a specific entity. For instance, "endoscopy" refers to the examination of internal structures, typically using a specialized instrument.

The other prefixes do not convey the idea of being 'inside.' For example, "post-" generally means 'after' or 'behind,' while "exo-" refers to something external or outside. The prefix "para-" typically implies something that is alongside or near rather than being within. Thus, "endo-" is the correct choice when identifying a prefix that suggests a position inside.