Step 1: Couple protection rate (CPR) is an indicator of the prevalence of contraceptive practice in a community. It is the percentage of eligible couples effectively protected against childbirth by an approved family planning method such as sterilisation, IUD, condom or oral contraceptive pills.
Step 2: The net reproduction rate (NRR) of 1 means each woman is, on average, replaced by exactly one daughter who survives to reproductive age - this represents the goal of achieving a stable, non-growing population.
Step 3: To reach NRR equal to 1, the couple protection rate must exceed 60 percent in the community.
Step 4: Therefore the required CPR is 60 percent, which is option B.