You have been called for a 77-year-old female with altered mental status. On scene, you note the patient's inability to speak and vomitus in her airway. Her breathing is labored and inadequate, and radial pulse rapid and weak. She is not moving her right arm or right leg. What should be your first priority?

A) Start positive pressure ventilation with supplemental oxygen
B) Administer glucose and immediately transport the patient to a stroke center
C) Suction the airway and determine adequacy of the breathing
D) Establish the time of stroke onset and start high-concentration oxygen

C) Suction the airway and determine adequacy of the breathing