This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
[{'content': 'Drug of choice for prophylaxis in diphtheria is: \nSelect and explain. \nA. Erythromycin, B. Doxycycline, C. Tetracycline, D. Clindamycin', 'role': 'user'}, {'content': "Answer: A \nExplanation: The options for chemoprophylaxis of diphtheria include Erythromycin (7-10 days oral course) or Benzathine Penicillin G (single intramucular dose). Ref: Erythromycin: A motilin Agonist and Gastrointestinal Prokinetic Agent: American Journal of Gastroenterology 88 (4): 485-90; Basic and Clinical Pharmacology By Katzung, 9th Edition, Section VIII; Park's Textbook of Preventive and Social Medicine By K. Park, 18th Edition, Page 104 and 19th Edition, Page 893", 'role': 'assistant'}]