Concept:Population growth is determined by changes in births, deaths, and the movement of people into or out of a country.
Explanation:Population size increases through births and immigration, and decreases through deaths and emigration.
The combined effect of these factors is known as natural increase plus net migration.
Fertility affects the number of births, while mortality affects the number of deaths.
Migration changes population size by adding or removing individuals from the population.
Net migration is the difference between the number of people entering and leaving a country.
Therefore, among the options given, net migration is the factor that directly influences population growth.
Dependency ratio, labour force, and per capita income are results or measures related to population structure, not determinants of population growth itself.
Answer:D. Net migration