Answer:
<em>For population increase two factors or ways are described which are birth or death, immigration and emigration.</em>
<em>The two ways a population can decrease is through mortality and emigration.</em>
Explanation:
<em>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.</em>
<em>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.</em>