What prefix would you associate with "not" or "absence of"?

The prefix that denotes "not" or the "absence of" is indeed "im-." This prefix is commonly used in the English language to negate the meaning of the word it precedes. For example, in words like "impossible," "imperfect," and "impolite," the "im-" prefix indicates a lack of the quality described by the base word. It effectively transforms the meaning to convey the opposite.

The other prefixes listed do not convey the same negation. "Inter-" typically refers to something being between or among, such as "international," which indicates something occurring between nations. "Endo-" is used to denote something that is within or inside, as seen in terms like "endoplasmic," referring to the lining of cells. "Infra-" generally means below or beneath, as used in terms like "infrared," indicating wavelengths below the visible spectrum. Thus, "im-" is the most appropriate prefix for expressing "not" or the "absence of" a particular quality.