End- means what?

• A. Within
• B. Under
• C. Nose
• D. Stone

Answer: (A)

The main idea here is that end- is a prefix meaning inside or within, showing something located or occurring on the inside of something else. In medical terms, end- helps describe inner parts or internal processes, like endocardium (inner lining of the heart) or endoscopy (looking inside a body part). That inner meaning makes it the best fit for “End- means what?” Among the options, only within captures that idea. The other choices point to different concepts: under is conveyed by prefixes like hypo- or sub-; nose would be linked to roots such as nas/o or rhin/o; stone would be lith/o.