**Core Concept**
The concept of population control through spacing between pregnancies is a key aspect of family planning and reproductive health. This approach involves delaying or spacing births to control family size, thereby reducing the overall population growth rate. It is a crucial strategy in maintaining a balance between population growth and resource availability.

**Why the Correct Answer is Right**
Spacing between pregnancies is an effective method of population control as it allows for adequate time for physical recovery, improved maternal and child health, and better economic opportunities for women. This approach also enables families to invest in their children's education, healthcare, and nutrition, ultimately leading to improved overall well-being. The spacing of pregnancies can be achieved through various methods, including the use of modern contraceptives, such as condoms, injectables, and oral pills. The World Health Organization (WHO) recommends a minimum of two years between consecutive births to ensure optimal health outcomes for both mothers and children.

**Why Each Wrong Option is Incorrect**
**Option A:** Education, although essential for overall development, is not a direct method of population control. Education can lead to better family planning decisions, but it is not a substitute for effective contraceptive methods.
**Option C:** Early sterilization, while effective in preventing further pregnancies, is a more permanent method that may not be suitable for all individuals, particularly those who may change their minds about family size or experience health issues.
**Option D:** Nutrition, while critical for overall health and development, is not a direct method of population control. Proper nutrition can support reproductive health, but it does not directly impact family size.

**Clinical Pearl / High-Yield Fact**
The "2-3-4" rule is a useful guideline for spacing between pregnancies. This rule suggests that a mother should wait at least two years between consecutive births, three years between the second and third births, and four years between the third and fourth births to ensure optimal health outcomes for both mothers and children.

**✓ Correct Answer: B. Spacing between pregnancies**