I think it’s the second one and the third one.
I hope this helps :)
One of the most important was climate changes. As climate changed, nomads had to find new places to migrate to which led to people going to areas that were uninhabited before. Another was the development of agriculture which more or less ended the nomadic way of life when people started settling.
Urbanization refers to the population shift from rural to urban areas, "the gradual increase in the proportion of people living in urban areas", and the ways in which each society adapts to the change.[1] It is predominantly the process by which towns and cities are formed and become larger as more people begin living and working in central areas.[2] The United Nations projected that half of the world's population would live in urban areas at the end of 2008.[3] It is predicted that by 2050 about 64% of the developing world and 86% of the developed world will be urbanized.[4] That is equivalent to approximately 3 billion urbanites by 2050, much of which will occur in Africa and Asia.[5] Notably, the United Nations has also recently projected that nearly all global population growth from 2017 to 2030 will be absorbed by cities, about 1.1 billion new urbanites over the next 13 years.
