**Core Concept**
The Net Reproduction Rate (NRR) is a demographic measure that indicates the number of daughters a woman would have in her lifetime, assuming a fixed sex ratio and mortality rate. Couple Protection Rate (CPR) is the percentage of couples using some form of contraception. To achieve a NRR of 1, the population would replace itself without growth.

**Why the Correct Answer is Right**
A NRR of 1 implies that each couple, on average, replaces itself with two children (considering both sexes), but since the question focuses on daughters, the calculation involves considering the proportion of the population that are females. Achieving this rate involves a significant portion of the population using effective contraception to control family size. The Couple Protection Rate (CPR) is crucial as it directly influences the NRR by reducing the number of births.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it underestimates the required CPR to achieve replacement level fertility.
**Option B:** Similarly, this option is too low to ensure that the population does not grow, as not enough couples would be using contraception.
**Option D:** This option overestimates or is not the minimum required to achieve a NRR of 1, as the exact percentage needed can be lower.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that achieving a NRR of 1 is crucial for population stabilization and requires a significant proportion of couples to practice family planning. The minimum CPR required to achieve this can vary but generally is considered to be around 60%.

**Correct Answer:** Correct Answer: C. 60%