Which of the following indicates choppy water during a rip current?

The presence of drifting debris and foam on the water's surface is a key indicator of choppy water associated with a rip current. When a rip current develops, it often disturbs the surface of the water, creating turbulence. This disturbance can stir up debris, seaweed, or other particles and also generate foam, making them visible. The appearance of such elements on the surface serves as a visual cue that a rip current may be active, signaling to swimmers and lifeguards alike to be cautious of the underlying water conditions.

In contrast, flat and calm water typically indicates no significant movement or currents present. Sudden waves colliding might suggest a different type of water condition but doesn’t specifically indicate a rip current. A smooth surface with occasional ripples would point towards stable and calm conditions, which are usually far from the tumultuous nature of a rip current.