Answer:
I am taking a S.S quiz o_o
In general, no, Mesopotamia did not fall because of attack from other empires, since it was primarily due to the Tigris and Euphrates Rivers drying up that led to a lack of produce, and therefore a fall in the empire itself.
The answer is (a.), Mahayana Buddhism is beliefs system did the win dynasty. Hope it helped you, and have a great day!
-Charlie
before the arrival of European settlers.