In a radial loop, the ridges flow in which direction?

• A. Toward the little finger.
• B. In a circular direction with no defined flow.
• C. Toward the thumb.
• D. Toward the index finger.

Answer: (D)

In fingerprint loops, the direction of ridge flow is described relative to the hand’s sides. A radial loop is defined by ridges entering from the thumb side and bending back toward that same side, so the flow is toward the thumb. The little finger side describes an ulner loop, and a circular or undefined flow fits a non-loop pattern, not a radial loop. Saying the flow is toward the index finger doesn’t align with the standard reference direction for radial loops. So the correct description is ridges flowing toward the thumb.