This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Social Science, Subject name: Social & Preventive Medicine
[{'content': 'Stage of contraction of family starts at - \nSelect and explain. \nA. Marriage, B. Birth of first child, C. Birth 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 Basic model of nuclear family life cyclePhases of family life cycleEvents characterizingNo. DescriptionBeginning of phaseEnd of phaseI FormationII ExtensionIII Complete extensionIV ContractionV Competed contractionVI DissolutionMarriageBirth of 1st childBirth of last child1st child leaves homeLast child has left home of parents1st spouse diesBirth of 1st childBirth of last child1st child leaves homeLast child leaves home of parents1st" spouse diesDeath of survivor (extinction)', 'role': 'assistant'}]