Answer:
The first action it's to determine the airway patency.
Step-by-step explanation:
After falling it is possible that the man has fractured various parts of his body and still survived, but if he is unable to breathe because of blood in his airways he will perish.
Checking if the patient can breathe is one of the most important first actions in helping someone. If the airways are blocked somehow any further effort to save him would be useless. That way we can first check the airways, mobilize his neck and provide oxygen then move him into the ambulance.