The world’s population is concentrated in certain countries like china most likely because of there being endemic diseases in the country. the lack of availability or lack of use of contraceptives. the emigration of people from more populated countries. the country’s land mass, which is much larger.

The world’s population is concentrated in certain countries like China most likely because of "the country’s land mass, which is much larger." China is considered as one of the largest nation. They are historically a home of various people around the world. Because of the country's population concentration, they implemented 'one-child policy.'