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': 'In a demographic cycle low stationary phase corresponds to which stage? \nSelect and explain. \nA. First, B. Fourth, C. Second, D. Third', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]