A nurse is caring for a client who has a peanut allergy. The client states, "I feel like my throat is closing" which of the following actions should the nurse take?

A. Deliver 2 L of oxygen via partial nonrebreather mask: While supplemental oxygen may support oxygenation, it does not treat the underlying life-threatening allergic reaction. Oxygen alone is insufficient for anaphylaxis and should not delay definitive treatment. B. Give epinephrine intramuscularly: Epinephrine is the first-line treatment for anaphylaxis and rapidly counteracts airway constriction, hypotension, and vascular permeability. Intramuscular administration in the mid-outer thigh provides rapid absorption and is essential to prevent respiratory compromise and shock. C. Notify the radiology department: Notifying radiology is unrelated to the acute management of an allergic reaction. Immediate intervention to secure the airway and treat anaphylaxis takes priority over nonessential notifications. D. Administer diazepam PO: Diazepam is an anxiolytic and has no role in managing anaphylaxis or airway obstruction. It does not reverse histamine-mediated effects and would delay critical emergency treatment.