You respond to a 51-year-old man found collapsed inside a closed garage. Bystanders have dragged him outside onto the lawn. He is unresponsive and does not appear to be breathing normally. You can clearly feel his carotid pulse. What is your next step?
a) Begin chest compressions
b) Administer a defibrillator shock
c) Perform a head tilt-chin lift
d) Check for foreign objects in the airway