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': 'Stage of contraction of family stas at ? \nSelect and explain. \nA. Marriage, B. Bih of first child, C. Bih of last child, D. Leaving home of first child', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is `d' i.e., Leaving home of first child", 'role': 'assistant'}]