Which morpheme means 'pertaining to'?

• A. Acr(o)
• B. Agora
• C. -ac
• D. Ad

Answer: (C)

In medical terminology, adjectives describing a relationship to something are often formed by adding a suffix that means “pertaining to.” The suffix -ac does exactly that: it turns a root into an adjective that describes a relation to the root’s meaning. For example, cardi- means heart, and adding -ac gives cardiac, meaning pertaining to the heart. The other options don’t convey that relation: acr(o) is a combining form with a different meaning (often related to sharp or a point), Agora is a standalone root meaning market, and Ad is a prefix meaning toward or toward, not a suffix indicating “pertaining to.” So the morpheme that means “pertaining to” is the suffix -ac.