This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Biostatistics, Subject name: Social & Preventive Medicine
To achieve a Net Reproduction Rate (NRR) of be 1 couple protection rate should be: 
Select and explain. 
A. 50%, B. 60%, C. 55%, D. 75%
B: 60%
Answer: B: 60% 
Explanation: Ans. b. 60%Ref: Parks Text book of Preventive and Social Medicine, 24th Ed; Page No-527NET REPRODUCTION RATE (NRR)NRR is demographic indicator.It is defined as the number of daughters a newborn girl will bear during her life time assuming fixed age specific fertility and mortality rates.COUPLE PROTECTION RATE (CPR)It is an indicator of prevalence of contraceptive practice in a community.CPR is percent of eligible couples (ECs) protected against one or the other approved method of family planning, viz. Condoms, OCPs, IUDs, sterilization.NRR=1 can be achieved if CPR>60%CPR (India): 47.1%(2106)Goal for CPR in RCH-II (2004-09): >65%(Goal by 2020 FP vision: 63.7%)CPR =x100