A 28-year-old develops severe anaphylaxis 10 minutes after ingesting peanuts. He has stridor, diffuse urticaria, wheeze, vomiting, and hypotension (BP 78/50 mm Hg; SpO2 88% on room air). What is the most appropriate immediate treatment?AIntravenous diphenhydramine 50 mg nowBAlbuterol-ipratropium nebulization with methylprednisolone 125 mg IVCIntramuscular epinephrine 0.3-0.5 mg (1 mg/mL) into the mid-anterolateral thigh nowDBegin epinephrine infusion only after central venous accessENormal saline bolus only, then observeCheck my answer