The natural barriers of this River Valley Civilization included the Himalaya Mountains and large deserts, but no natural barrier in the north (which made them build a wall as a barrier).
Your answers
Mesopotamia
Egypt
China
India

is there a answer choice?

by using  production possibilities graph.  opportunity costs are key expenses in financial matters and are utilized as a part of registering money saving advantage investigation of a venture. such expenses, be that as it may, are not recorded in the record books but rather are perceived in basic leadership by processing the money costs and their subsequent benefit or misfortune.

debating and finalizing the detail of the policy

it's