In the case of an unresponsive pedestrian following a vehicle collision, what is the first step you should take?

In the scenario involving an unresponsive pedestrian after a vehicle collision, the first step to take is to assess the airway. The most crucial immediate concern in managing an unresponsive individual is ensuring that their airway is clear. This is because an unresponsive state can lead to airway obstruction due to the tongue falling back into the throat or other debris that may hinder breathing.

By suctioning the airway, you are addressing a life-threatening condition. If the airway is not patent, the victim cannot breathe, leading to respiratory arrest and potential death. This thorough assessment allows you to take necessary actions to maintain or restore effective breathing.

The other options involve procedures and assessments that are important in a full patient evaluation, but they do not address the immediate life-threatening concern of airway management. Checking for a pulse, determining blood pressure, or administering oxygen would all follow after you ensure the airway is clear and patent. Therefore, the priority in this emergency response situation is the maintenance of an open airway.