Well I think the answer might be D.
Answer:
Climate change, Availability of resources
Explanation:
1. Soon enough when the climate on the planet started to become more arid and become too hot, so humans started to migrate from Africa.
2. People started to move away to the places where resources were available.
Stone mason and concrete but their concrete that they used was one of a kind but nobody knows their recipey to make it
Conducting elections hope it helped
