When is international migration directly included in national population change?

Correct answer: When people enter or leave by crossing a national border

The direct answer is option A. International migration occurs when people move across the boundary of one country and another country. A person entering a country is an international in-migrant, while a person leaving it is an international out-migrant. These movements directly affect the country’s total population: arrivals add people and departures remove people. Option B describes a very local move and does not cross a national boundary. Option C concerns the balance of natural change; equal births and deaths would make natural increase zero, but this statement is not international migration. Option D concerns area and has no direct connection with people crossing borders. A useful relationship is: population change = births minus deaths plus in-migration minus out-migration. Memory cue: for national migration effects, look first for a national border.