A pediatric patient presents to the emergency department with complaints of shortness of breath, increased work of breathing, and a cough. The patient is alert and oriented at times 3, skin is pink, warm and dry. BP 112/68, T99, P106, RR 32. pulse oximetry 90% on room air. Assessment of the lung sounds reveals diminished lung sounds throughout all lung fields. The patient has a past medical history of peanut allergy. The mother tells you that they were at a birthday party and after consumption of a cupcake, the symptoms started. The nurse anticipates that which of the following medications will likely be ordered for this patient?

A. Cetirizine (Zyrtec): Cetirizine is an antihistamine used to treat mild allergic reactions, such as seasonal allergies or mild hives. It is not the treatment of choice for severe allergic reactions like anaphylaxis, which this patient may be experiencing given the symptoms and history of peanut allergy.
B. Diphenhydramine (Benadryl): Diphenhydramine is an antihistamine that can be used for mild to moderate allergic reactions, including urticaria and mild anaphylaxis. While it may be part of anaphylactic treatment, it is not the primary treatment for severe symptoms like difficulty breathing.
C. Guaifenesin: Guaifenesin is an expectorant used to relieve chest congestion and make coughs more productive. It is not appropriate for treating allergic reactions or respiratory distress related to anaphylaxis.
D. Epinephrine: Epinephrine is the first-line treatment for anaphylaxis, which is a severe and potentially life-threatening allergic reaction. It works by rapidly reducing airway swelling, improving breathing, and stabilizing blood pressure. Given the patient's symptoms and history of peanut allergy, epinephrine is the most appropriate medication.