Which was the most prevalent mode of the post-classical world: exchange, imitation. or rejection?

The Post-Classical era was the time between the 5th and 15th centuries C.E.The most prevalent mode of the Post-Classical world were EXCHANGE AND IMITATION. During this time, a world network was developed. The international trade allowed intellectual and material exchanges. These exchanges paved the way for imitation of established centers. Less organized civilizations attempted to imitate the more organized civilizations. 

the western roman empire flourished, but the eastern portion of the empire struggled.

the answer is a. apartheid.