A client scheduled for a carotid endarterectomy requires insertion of an intra-arterial blood pressure-monitoring device. The nurse plans to perform the Allen test. Which observation indicates patency of the ulnar artery?

A Blanching of the hand on compression and release of the ulnar artery B Muscular twitching of the bicep muscle with use of a tourniquet at the wrist C Hand turning pink after the nurse releases the pressure on the ulnar artery D Flexion of the wrist when tapping the ulnar artery with a reflex hammer