**Core Concept**
The demographic goal of Net Reproduction Rate (NRR) = 1 is a measure of population replacement, indicating that each generation of women is replacing itself with the next. This is influenced by the Contraceptive Prevalence Rate (CPR), which is the percentage of women of reproductive age using some form of contraception. Achieving NRR = 1 is crucial for population stabilization.

**Why the Correct Answer is Right**
To achieve NRR = 1, the CPR must be sufficiently high to reduce the total fertility rate (TFR) to replacement level, which is approximately 2.1 children per woman in most countries. A high CPR indicates widespread use of effective contraceptive methods, leading to fewer unplanned pregnancies and lower fertility rates.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because a lower CPR would not be sufficient to achieve the desired reduction in fertility rates.
**Option B:** Incorrect as it does not specify the threshold required for achieving NRR = 1.
**Option D:** Incorrect because it exceeds the generally accepted threshold for achieving replacement-level fertility.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that small changes in CPR can significantly impact population growth rates over time, making family planning a critical component of public health strategies.

**Correct Answer:** Correct Answer: B. 60%.