Which action must be taken to rescue a responsive guest in distress who is below the surface and beyond arm's reach?

To successfully rescue a responsive guest in distress who is below the surface and beyond arm's reach, it is essential to perform specific actions effectively. The correct choice involves all steps necessary except for removing the rescue tube strap.

When a guest is in distress and submerged, the lifeguard must prioritize safety while also ensuring that the guest can be reached and assisted promptly. Calling for additional help is a critical step, as other trained personnel may be needed to assist in the rescue, depending on the situation's severity.

Performing a rescue dive is an appropriate action since it allows the lifeguard to reach the guest directly and provide immediate support. However, keeping the rescue tube strap on the lifeguard ensures that they can maintain buoyancy and safety during the dive and subsequent rescue attempts. By not removing the strap, the lifeguard maintains the ability to use the flotation device effectively if the rescue requires bringing the guest to the surface.

This choice highlights the importance of a coordinated approach to water rescue, where safety protocols and techniques are combined to effectively assist someone in distress without putting the rescuer at risk.