Answer:
For population increase two factors or ways are described which are birth or death, immigration and emigration.
The two ways a population can decrease is through mortality and emigration.
Step-by-step explanation:
A population's increase is resolved by death, birth, immigration, and emigration. When a population's birthrate is higher than its death rate the population size, The population size is rises.
Also,The two factors responsible for the decrease in size of a population are emigration, which is the migration of an individual from a place. and mortality, which is the number of individual deaths in a population over a period of time.