Final answer:
In a situation where you are babysitting and the infant is unresponsive, it's essential to call 911 first and then begin CPR starting with the ABC's of CPR, ensuring professional medical assistance is on its way while you provide immediate aid.
Step-by-step explanation:
If you're babysitting your infant nephew and find him unresponsive, the best action to take is to phone 911 immediately to ensure that advanced life support is on its way, and then return to the infant to begin the ABC's of CPR (choice a). It is critical to establish professional help is on the way as soon as possible. Once you have called for help, you would then focus on providing CPR, starting with checking the airway, providing rescue breaths, and commencing chest compressions following the guidelines provided for infants, which is different from adults. Cardiopulmonary resuscitation (CPR) is a lifesaving technique useful in many emergencies, including a situation where an infant's breathing or heartbeat has stopped. Proper hand placement and depth of compressions are vital for effective CPR, and current standards advocate for a chest compression rate of 100 per minute.