This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
[{'content': 'For which of the following are live vaccines used - \nSelect and explain. \nA. Measles, B. Cholera, C. Small pox, D. Oral Polio', 'role': 'user'}, {'content': 'Answer: A \nExplanation: live attenuated vaccines used for prophylaxis of measels REF:ANATHANARAYANAN MICROBIOLOGY NINTH EDITION PAGE.514', 'role': 'assistant'}]