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': 'Who is the chief of WHO ? \nSelect and explain. \nA. Tedros Adhanom, B. Harshvardhan, C. António Guterres, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]