Final answer:
In this situation, the rescuers should start CPR beginning with compressions. CPR can help maintain blood flow and oxygenation until advanced medical help arrives.
Step-by-step explanation:
The child is gasping for breath but has a pulse rate of 100 per minute. In this situation, the rescuers should start CPR beginning with compressions (option a). Gasping for breath is a sign of a severe cardiac emergency, and the child may not be getting enough oxygen. CPR can help maintain blood flow and oxygenation until advanced medical help arrives.