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: Social & Preventive Medicine
[{'content': 'Carrier state is seen in following, except: \nSelect and explain. \nA. Diphtheria, B. Measles, C. Typhoid, D. Polio', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Measles', 'role': 'assistant'}]