As early humans moved into river valleys, what were some of the contributing factors that contributed to epidemics? (check all that apply)

Why was the al-qaeda terrorists organization established

This law states that the "chinese laborers to this country endanger the good order of certain localities" in the united states. which of these would represent a "locality" that would most likely have wanted this law created and passed? a) dallas b) chicago c) atlanta d) san francisco

What is the main social system that existed in ancient china?