What is the meaning of the prefix "anti-"?

The prefix "anti-" is derived from Greek, meaning "against" or "opposite." In medical terminology, it is used to indicate opposition or counteraction. For example, in terms like "antibiotic," the "anti-" prefix signifies that the substance works against bacteria. This foundational understanding of the prefix helps in interpreting a wide range of medical terms where it is applied to express a counter or opposing effect. The other choices do not align with this specific meaning; "two" refers to a numerical value, "without" indicates a lack or absence, and "other" is too vague and does not convey a clear idea relevant to the prefix in question.