In which scenario should a lifeguard use rescue breathing?

Rescue breathing is indicated when a victim is not breathing but still has a pulse. In this scenario, the victim requires assistance to provide adequate oxygen to their body, as they are unable to breathe on their own. By administering rescue breaths, a lifeguard can help maintain oxygen flow to vital organs until the victim resumes normal breathing or professional medical help arrives.

The other scenarios do not warrant the use of rescue breathing. If the victim is breathing normally, as suggested in the first option, they are receiving adequate oxygen without assistance. A conscious and alert victim, as described in the third option, typically does not require rescue breathing since they are able to control their own breathing effectively. Lastly, the presence of multiple victims does not influence the decision to administer rescue breathing unless one of them is specifically in a situation where they are unresponsive and not breathing while having a pulse. In this case, priority should still be given to the individual in need of airway support.