What is the recommended action if a swimmer is unable to keep their head above water?

The recommended action in the scenario where a swimmer is unable to keep their head above water is to perform a rescue according to the situation. This choice is correct because lifeguards are trained to assess each rescue situation carefully. They take into account the swimmer's condition, the environment, and their own safety before initiating a rescue.

Performing a rescue may involve different methods such as reaching out with a rescue buoy, extending a pole, or, in some cases, entering the water, depending on the urgency of the situation and the lifeguard's training. It's crucial to act promptly but also safely to avoid putting oneself at risk.

The other choices do not provide the appropriate response: alerting other swimmers does not address the immediate danger to the distressed swimmer; jumping in without hesitation can lead to additional risks for both the rescuer and the swimmer; and waiting for someone to signal for help can result in delays that could be dangerous in an emergency. Immediate and informed action, tailored to the situation, is essential for effective rescue operations.