C. Continue to monitor the patient while
maintaining an open airway.
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option A) is stupid. let the ambulance come, don't cancel 911. lol
option B) is also stupid, you don't need to keep ventilating the dude, he's breathing on his own.
option D) is stupid because if you are not a doctor then you won't have the equipment to obtain an AED to check the heart.
THEREFORE, option C) is the best.