This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Demography and Family Planning, Subject name: Social & Preventive Medicine
In basic model of Nuclear family life, the phase of family life cycle beginning with birth of last child and ending with leaving of home of first child is known as? 
Select and explain. 
A. Formation, B. Extension, C. Complete extension, D. Contraction
C: Complete extension
Answer: C: Complete extension 
Explanation: Ans. c (Complete extension) (Ref. Park Textbook of PSM 22nd/pg.635)A family is a primary unit in all socities. Familes are not constant. A normal family-cycle is generally conceived as having six phases as follows:BASIC MODEL OF NUCLEAR FAMILY LIFE CYCLE Phase of family cycleCharacterizing EventsNo.DescriptionBeginning of phaseEnd of phaseIFormationMarriageBirth of 1st childIIExtensionBirth of 1st childBirth of last childIIIComplete extensionBirth of last child1st child leaves homeIVContraction1st child leaves homeLast child has left home of parentsVCompleted contractionLast child has left home of parents1st spouse diesVIDissolution1st spouse diesDeath of survivor (Extinction)