Water Safety Instructor (WSI) Practice Exam

The choice indicating that the front crawl and back crawl utilize a body roll during execution is accurate because both strokes involve rotational movements of the torso in order to facilitate proper technique and efficiency.

In the front crawl, swimmers engage in a body roll as they turn their body to the side to breathe. This motion allows for a streamlined position in the water, which helps to reduce drag. Additionally, the rolling motion aids in the coordination of arm strokes and leg kicks, promoting a more fluid swimming technique.

Similarly, in back crawl, the swimmer also utilizes a body roll to maintain balance and alignment while performing the stroke. The roll helps in activating the core muscles, allowing the swimmer to keep their hips high and maintain a streamlined position. This facilitates greater propulsion through the water by maximizing the effectiveness of both arm movements and leg kicks.

In contrast, the other strokes listed in the other choices either do not incorporate body rolls or use them in a limited capacity, which is why they do not match the characteristics of strokes where body roll is a significant component of the technique.