In which condition will international migration directly affect a country’s population?

Correct answer: When people cross a national border and settle

Direct answer: Option A. International migration occurs when people move across the national boundary of one country to live or settle in another country. Step 1 is to identify whether a country-to-country border has been crossed. Step 2 is to distinguish migration from a short visit or temporary travel; the question describes people settling. Step 3 is to see the population effect: the receiving country gains people and the sending country loses people, apart from any later births or deaths. Option A gives exactly this condition. Option B is local or internal movement because no national border is crossed. Option C concerns the relationship between births and deaths and says nothing about migration. Option D rules out movement altogether, so it cannot describe international migration. Memory cue: international means between nations; crossing a national border is the essential clue.