What influences the size of a population?

The size of a population is influenced by various factors, and immigration and emigration patterns play a crucial role in determining population dynamics. Immigration refers to the arrival of individuals into a population from other areas, which increases the population size. Conversely, emigration involves individuals leaving a population to settle in another area, which decreases the size. Together, these two processes directly affect population growth and decline by altering the number of individuals in a particular area.

In addition to immigration and emigration, other factors such as birth rates and death rates also contribute to population size, but the correct answer highlights the importance of movement patterns. Environmental factors can influence these patterns, but they do not singularly determine population size. Thus, understanding the interplay between immigration and emigration is essential to grasp how populations change over time.