A

An unconscious yet breathing patient should first be positioned supine (recline the dental chair), while the dentist calls for help and administers high-flow oxygen; airway and breathing are already present, so CPR or intubation are not indicated at this stage, and ECG can wait. This follows the dental P-A-B-C-D emergency algorithm, where “P” (position) and oxygenation are the immediate priorities for an unconscious patient who is still breathing [Reed, 2010, PMID 20436086].