B. Pax Mongolica. In Pax Mongolica, there is relative peace that happened after Kublai Khan was killed. Resulting to this, the re-opening of Silk Road gave way to transfer to culture, tradition, and trades, and religion.
Through time they changed it based on problems on hand, and the changes through time.
Sorry if that's not a sutable answer
Answer:
what I think it is in my opinion is D
Because they help each other and became wealthy