Which are two ways a population can decrease in size

a) immigration and emigration

b) increase death rate and immigration

c) decrease birthrate ans emigration

d) emigration and increase birthrate

The answer is option C.

Explanation:

The contrast among "move" and "emigrate" is that "moving" is the demonstration of entering a remote nation to live while "emigrating" is the demonstration of leaving a nation to live in another. Emigrate intends to abandon one's nation to live in another. Move is to come into another nation to live for all time. Move is to move, similar to feathered creatures in the winter. The decision among emigrate, immigrate, and relocate relies upon the sentence's perspective.

The answer would be c in my opinion because less people means less population