You have encountered a person who is apparently unconscious and unresponsive. There is no rise and fall of the chest, and you can hear no breath sounds. You should first
(A) begins mouth-to-mouth rescue breathing, giving two full breaths
(B) proceed with the Heimlich maneuver
(C) being with 30 external chest compressions at a rate of 100 compressions/min
(D) begin with 5 external chest compressions at a rate of 50 compressions/min