Which of the following is an example of a combining form?

• A. cardi/o
• B. hypo-
• C. -ectomy
• D. gastritis

Answer: (A)

Combining forms are roots paired with a vowel that lets them attach to other word parts to form medical terms. cardi/o fits this pattern because cardi- is the root meaning heart, and the added o serves as the linking vowel to join with endings or prefixes (for example, cardiology or cardiac). The other options aren’t combining forms: hypo- is a prefix meaning under or below and sits at the start of a term; -ectomy is a suffix meaning surgical removal; gastritis is built from the root gastr- (stomach) plus the suffix -itis (inflammation), not a combining form itself.