This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Non communicable diseases, Subject name: Social & Preventive Medicine
The net reproduction rate of 1 can be achieved only if the following rate exceeds 60%- 
Select and explain. 
A. Total feility rate, B. Total marital feility rate, C. Age-specific marital feility rate, D. Couple protection rate
D: Couple protection rate
Answer: D: Couple protection rate 
Explanation: Park's textbook of preventive and social medicine 23rd edition. * Demographers are of view that demographic goal of NRR=1 can be achieved only if CPR exceeds 60%.