You respond to a residence for a 28-year-old male with a reported allergic reaction. On arrival, the patient states he was stung by a bee about 10 minutes ago. He has hives across his chest, audible stridor, and is speaking in short sentences. His BP is 88/60 mmHg, HR is 124, RR is 24, and SpO₂ is 91% on room air. He has a prescribed epinephrine auto-injector but has not used it. Which of the following is the most appropriate next action? A. Apply high-flow oxygen via NRB mask and transport immediately, monitoring en route. B. Assist the patient in administering his epinephrine auto-injector and prepare for rapid transport. C. Administer oral diphenhydramine (Benadryl) from your jump bag and reassess in 5 minutes. D. Place the patient supine with legs elevated and contact medical direction before any intervention.