SCENARIO 1: You witness a middle-aged, obese male pedestrian collapse on an escalator in an airport. He is clutching his chest and slumps over on the person behind him. The bystander places him on the floor at the end of the down-moving escalator track. As a first responder certified in ACLS, which of the following is your first course of action?
a) Begin chest compressions
b) Administer high-flow oxygen
c) Call for emergency medical services (EMS)
d) Assess airway and breathing