Question

a common medical word root that means \back\ is:

Explanation:

In medical terminology, the word root "posterio - " (from the option "posterior" - likely a typo or misdisplay, but the correct medical root for "back" related to posterior/anterior axis is "poster - " or the root related to "back" in position is "dors - "? Wait, no, let's recall: "posterior" refers to the back (dorsal) side in anatomical terms. Wait, the options seem to have "posterior" (correct medical term for back - related, as anterior is front, posterior is back in anatomy). Wait, maybe the options are: posterior, dorsal, anterior, ventral? Wait, the user's image has options, maybe the first option is "posterior" (spelled as "posterio" maybe a typo). So the correct medical word root (or term) meaning "back" is posterior (as posterior in anatomy means the back side, opposite of anterior).

Answer:

A. posterior (assuming the first option is posterior, as it's the medical term meaning "back" in anatomical terms)