The prefix 'retro' means which direction?

• A. Forward
• B. Below
• C. Toward
• D. Backward

Answer: (D)

The direction concept being tested is that retro- denotes backward or behind. The prefix comes from Latin retro, meaning back. In medical terms, retro- is used to indicate movement toward the back or position behind another structure (for example, retroflex means bending backward, retroperitoneal means located behind the peritoneum, or retrograde meaning moving backward through a system). Since the question asks for a directional meaning, backward is the correct fit. Other directions use different prefixes—forward would be indicated by other roots like pro- or ante-, below by sub- or inferior-, and toward by ad-—so retro clearly signals backward.