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': 'Cyclic trends are seen in which of the following - \nSelect and explain. \nA. Rabies, B. Measles, C. Cholera, D. Hepatitis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]