This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infection, Subject name: Medicine
[{'content': 'What is the diagnosis in this patient who appeared sick, had a bull neck, and was tachycardic? \nSelect and explain. \nA. Diphtheria, B. Epiglottitis, C. Infectious mononucleosis, D. Rheumatic fever', 'role': 'user'}, {'content': "Answer: A \nExplanation: Answer A. DiphtheriaThe patient's features are typical of diphtheria. Her throat culture was positive for Corynebacterium diphtheriae. The patient recovered after the initiation of treatment with penicillin.", 'role': 'assistant'}]