In which condition can international migration change a country's service planning?

Correct answer: When many people come to settle in the country

Direct answer: A, when many people come to settle in the country. International migration changes the population of a country when people cross a national boundary and live in the destination country. A large inflow can increase demand for schools, hospitals, housing, transport, water supply, sanitation, and employment services. Planners must therefore count the additional population, estimate its needs, and expand or redistribute facilities. The reasoning is simple: international arrivals increase the number of residents; more residents create greater demand; service planning must respond to that demand. A is correct because large-scale settlement can alter both the amount and location of required services. B describes local movement within one village, not international migration. C states that migration is absent, so it cannot show an effect of international migration. D concerns physical drainage and does not directly explain population-service planning. Memory cue: when population moves across a border and settles, planners must plan for the people as well as the place.