What is the correct sequence of basic life support for an unresponsive adult?

The current basic life support sequence for an unresponsive adult follows C-A-B: compressions, airway, breathing. First, confirm unresponsiveness and call for help. Activate the emergency response system and get a defibrillator. Begin chest compressions immediately: push hard and fast at a rate of 100 to 120 compressions per minute, at a depth of at least 2 inches, allowing full chest recoil. After 30 compressions, open the airway with head-tilt chin-lift and give 2 breaths. Continue the 30 to 2 cycle. When the defibrillator arrives, apply it immediately.