Natural Population Growth Formula

Steps:

• Define natural population growth as the change due to births and deaths only, ignoring migration.
• Recall the formula: natural increase = birth rate - death rate.
• Identify options: A includes migration, B has birth and death rates, C mixes emigration and death, D focuses on migration.
• Select the option matching the formula exactly.

Why B is correct:

• Natural population growth is calculated as birth rate minus death rate, per demographic definitions, excluding all migration effects.

Why the others are wrong:

• A: Includes net migration, which affects total growth, not natural growth.
• C: Emigration is a migration factor, not part of natural (vital events only) growth.
• D: Immigration and emigration determine net migration, irrelevant to natural growth.

Final answer: B