How Did Sharing a Common Border Affect Relations Between the Inland

How did sharing a common border affect relations between the inland empires of Wari and Tiwanaku?

A) They exchanged knowledge,as seen in the Tiwanaku adoption of the hillside terracing style of farming developed by the Wari.
B) They appeared to get along because there was little overt conflict or warfare between them.
C) People living along the border intermarried and created a hybrid culture that became the common culture of the entire Andean region over time.
D) Caravans of llamas from each empire gathered at the border to trade goods.