Which combining form means on top of?

• A. Epi-
• B. Em-
• C. -emia
• D. Endo

Answer: (A)

The main idea here is identifying a combining form that expresses a position relative to another structure. epi- means on top of or upon, and is used in terms that denote something located on the surface or outer layer, such as epidermis (the outer layer of skin above the dermis), or epiglottis (the flap of cartilage at the top of the larynx).

The other options don’t convey a surface-on-top relationship: em- typically relates to being in or into a space, endo- means within or inner, and -emia refers to a blood condition. So epi- is the combining form that correctly means on top of.