You are by the side of a 64-year-old male patient who collapsed at home. After assessing his level of consciousness, airway, and breathing, you determine that he is unresponsive with an open airway, but not breathing. What instruction should you immediately give your partner?

A) "Let's place an oral airway and start ventilations."
B) "Please check his blood pressure and skin temperature."
C) "Go ahead and apply the automated external defibrillator."
D) "We will need to start cardiopulmonary resuscitation."

A