You are off duty at a park when you witness an apparently healthy 12-year-old child suddenly collapse. there are no bystanders around and your mobile phone is in your car. after confirming that the child is in cardiac arrest, you should: select one:
a. perform chest compressions only until a bystander arrives.
b. call 9-1-1 and then return to begin cpr on the child.
c. perform cpr for 2 minutes and then call 9-1-1.
d. deliver five rescue breaths before starting chest compressions