What was one of the primary results of chinese civilizations settling in river valleys?

a-the people learned to control flooding.
b-the culture created a writing system.
c-the fertile land supported a food surplus.
d-the rulers adopted a system of divine leadership.

The best and most correct answer among the choices provided by the question is the third choice "fertile land supported a food surplus."

Probably the primary result of Chinese civilizations settling in the river valleys was that they were able to produce more crop.

I hope my answer has come to your help. God bless and have a nice day ahead!