Final answer:
When alone and helping a child with cardiac arrest, a responder should perform CPR, call for emergency help, and use an AED if available. The correct action is all of the above.
Step-by-step explanation:
If a responder is alone and helping a child with cardiac arrest, the best course of action would be to: 1) Perform CPR, 2) Call for emergency help, and 3) Use an AED if available. Therefore, the correct answer is 4) All of the above. It is vital to initiate CPR (cardiopulmonary resuscitation) immediately to maintain blood flow, especially to the brain, to prevent irreversible damage. After beginning CPR, it is important to call for emergency help promptly. If an AED (automated external defibrillator) is accessible, it should be used as soon as possible. AEDs are designed for public use, providing verbal instructions and automatically analyzing the patient's heart rhythm to deliver a shock if needed.