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': 'Population control can be best achieved by \nSelect and explain. \nA. Education, B. Spacing between pregnancies, C. Early sterilization, D. Nutrition', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]