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': 'Koplik spots of measles seen near \nSelect and explain. \nA. Upper 2nd molar, B. Lower 2nd molar, C. Lower 2nd premolar, D. Upper 2nd premolar', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]