Which option gives the correct data requirement for population change?

Correct answer: Births, deaths, in-migration, out-migration and time period

The direct answer is A. To measure population change, we need data on the processes that add or remove people and the period over which they occurred. Births add people, deaths remove people, in-migration adds residents to an area, and out-migration removes residents. The time period is essential because a number has meaning only when we know whether it occurred in a month, year or another stated interval. Step 1: collect births and deaths. Step 2: collect people moving in and out. Step 3: specify the same time period and combine the figures with correct signs. Option A contains this complete minimum set. B concerns physical geography, C concerns vegetation and wildlife, and D describes cultural features; none directly measures demographic change. Memory cue: population change needs “who was added, who was lost, and during which time.”