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': 'Which of the following stages of demographic cycle has declining population: \nSelect and explain. \nA. Second, B. Third, C. Fouh, D. Fifth', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Fifth stage (declining): Population begins to decline because the bih rate is lower than the death rate. Ref: Park, 22nd edition pg: 441', 'role': 'assistant'}]