How were Native Americans affected by national expansion? O A. They migrated to big cities in the East.
O B. They became rich by selling land to settlers.
C. The helped settlers establish farms.
O D. They were forced to move to reservations.

explanation:

the addition to geographic boundaries that might have  kept the people of the huang river civilization from traveling to far distance region is that they had learned about the other river valley civilizations but feared contact would bring invasion.

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