All of the Following Factors Contribute Significantly to the Rate

All of the following factors contribute significantly to the rate of change of a country's population except which?

A) life expectancy (the average number of years a population lives from birth)
B) immigration (the number of people who enter a country for the purpose of permanent residence)
C) population density (the total number of people per square mile/kilometer)
D) birth rate (the number of births during a specified time period)
E) death rate (the number of deaths during a specified time period)