This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Social science, Mental health & Genetics, Subject name: Social & Preventive Medicine
Extension phase of a nuclear family begins with - 
Select and explain. 
A. Marriage, B. Bih of the fibrst child, C. Bih of second child, D. Spouse death
B: Bih of the fibrst child
Answer: B: Bih of the fibrst child 
Explanation: phase 1 ; formation - begins with marriege and ends with bih of first child 2; extension - from bih of first child to bih of last child 3 ; complete extension - from bih of last child to 1st child leaves home 4; contraction - from 1st child leaves home to last child leaves home of parents 5; completed contraction - from last child has left home of parents to 1st spouse dies 6; dissolution- from 1st spouse dies to death of survivors ref ;(page no;683)23rd edition of PARK&;s textbook of Preventive and Social medicinel medicine