When does a change take place in a demographic transition? 

A)  Change occurs when either immigration or emigration changes the population growth pattern. 
B)  Change occurs when the birth rate drops below the death rate. 
C)  Change occurs when the economic development of a country changes the population growth pattern. 
D)  Change occurs when one-third of the population is under 15 years of age.

Demographic Transition

A model that describes the transformation of a country from high birth and death rates to low birth and death rates as a society progresses economically.

Population Growth

The increase in the number of individuals in a population, often measured by birth rate minus death rate plus migration.

Economic Development

Economic Development refers to the process by which a region improves the well-being of its citizens through economic growth, redistribution of wealth, and improvements in quality of life.