d.
explaination:
The writings of a religion can spread around quickly. Take as an example Egypt's religion and their various gods.
I think it is d but it also might be b but just go with d. it sounds more correct
<span>Both the Arab and Mongol Empires has periods of intellectual expansion. but the Arab Empire was created due to the rise of Islam and the Mongol empire was created due to the Mongols tearing away from Mongolia.</span>
