Under what circumstances might a rescuer stop performing CPR?

A rescuer may stop performing CPR under several circumstances that indicate either the victim's condition has changed positively or when they can no longer continue effectively. If the victim starts to breathe on their own, this signals that the airway is clear and circulation has resumed, allowing the rescuer to safely stop CPR.

The arrival of a trained responder, such as an EMT or paramedic, is another critical moment. These professionals have the training and equipment to take over care, ensuring the victim receives the best possible treatment. It's important for bystanders to understand that professional responders have the knowledge to manage the situation more effectively.

Feeling fatigued is also a legitimate reason to cease CPR. The effectiveness of chest compressions relies heavily on the rescuer's ability to maintain quality and depth. If the rescuer is too tired, their compressions may become ineffective and could further compromise the victim's chance of recovery.

In summary, all these reasons—resuming breathing by the victim, the arrival of trained personnel, and the capability of the rescuer to continue—constitute valid situations for stopping CPR, making "all of the above" the correct choice.