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': 'Iodine deficient population in the world is: \nSelect and explain. \nA. 20 million, B. 12 million, C. 9 million, D. 6 million', 'role': 'user'}, {'content': 'Answer: A \nExplanation: 20 million', 'role': 'assistant'}]