Correct Option: D. the annual death rate Explanation of the Correct Answer To calculate the annual natural growth rate of a country's population, we need to understand what "natural growth" means. The natural growth rate is the difference between the number of births and the number of deaths in a given year, expressed as a percentage of the total population. The formula for calculating the natural growth rate can be expressed as: [ \text{Natural Growth Rate} = \left( \frac{\text{Births} - \text{Deaths}}{\text{Total Population}} \right) \times 100 ]

1. Birth Rate: This is the number of live births per 1,000 people in a year. It provides the number of new individuals being added to the population.
2. Death Rate: This is the number of deaths per 1,000 people in a year. It accounts for the number of individuals leaving the population due to mortality.
3. Natural Growth Rate Calculation: By subtracting the number of deaths from the number of births, we can determine how many people are being added to the population through natural means (i.e., without considering migration). This difference is then divided by the total population to find the growth rate as a percentage.

Why the Other Options Are Incorrect

• Option A: the size of that country While the size of the country (geographically) may influence population density and distribution, it does not directly affect the calculation of the natural growth rate. The natural growth rate is concerned with births and deaths, not the physical size of the country.
• Option B: the rate of immigration into that country Immigration affects the overall population size but does not factor into the natural growth rate. The natural growth rate specifically looks at the births and deaths within the population, excluding any changes due to migration. Therefore, while immigration can influence total population growth, it is not relevant for calculating the natural growth rate.
• Option C: the population census of that country A population census provides a snapshot of the total population at a specific point in time, which can be useful for understanding demographic trends. However, it does not provide the necessary data for calculating the annual growth rate, which requires annual figures for births and deaths. The census data is more about the population size rather than the dynamics of growth.

Summary of Key Points

• The natural growth rate is calculated using the formula: (\text{Natural Growth Rate} = \left( \frac{\text{Births} - \text{Deaths}}{\text{Total Population}} \right) \times 100).
• The annual death rate is essential for determining how many individuals are leaving the population, which is necessary for calculating the net growth from births.
• Other factors like immigration, geographic size, and census data do not directly contribute to the calculation of the natural growth rate.
• Understanding the components of population change (births and deaths) is crucial for analyzing demographic trends.

Revision Summary

• The natural growth rate is determined by the difference between the birth rate and the death rate.
• The formula for natural growth rate involves births, deaths, and total population.
• Immigration and geographic size do not affect the natural growth rate calculation.
• Accurate data on births and deaths is essential for demographic analysis.