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': 'If annual growth rate of a population is 1.5-2%, what number ofyears will be required to double the population? \nSelect and explain. \nA. 70-47 years, B. 47-35 years, C. 35-28 years, D. 28-23', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e. 47-35 years", 'role': 'assistant'}]