Your patient is a 24-year-old female who swallowed a handful of pills of unknown type. Although she was initially alert and oriented with no complaints, you note that she is now beginning to slur her words and is becoming progressively lethargic. What is the highest priority in dealing with this patient?

A) Maintaining an open airway
B) Checking the patient's pupil size and reactivity to light
C) Finding out exactly what she took
D) Notifying the receiving facility of the change in mental status

A