A reader can tell that the meaning of "obnoxious" will include "having the quality of something" because of the. A) prefix B) pronunciation C) suffix D) word root

I believe the answer is: C. suffix

Suffix refers to a morpheme added at the end of a word that create additional meaning for the word.

-ous suffix is added to a word in order to transform the word into adjective, more specifically adjective that describe someone's personality

A reader can tell that the meaning of obnoxious will include having the quality of something because of the suffix - ous. That suffix is generally used for adjectives, so we know that it is used to show us a quality.