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': 'The only disease which has been eradicated ? \nSelect and explain. \nA. Chickenpox, B. Smallpox, C. Measles, D. Measles', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. is \'b\' i.e., Smallpox "Today, smallpox is the only disease that has been eradicated".', 'role': 'assistant'}]