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: Dental
[{'content': 'Where was the atraumatic restorative treatment first introduced? \nSelect and explain. \nA. Tanzania, B. China, C. U.S.A., D. New Zealand', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]