What effect did the yuan dynasty have on chinese culture?

For outsiders to conquer China successfully from historical precedent: 
1) China needs to be at least one of the following: divided, weak, corrupt, engaged in civil war 
2) You need to massacre as many chinese as possible 
3) Once conquered you need to use them in your government to rule. If the disparity in status is too great you will be overthrown sooner rather than later. If there is at least some respect for ethnic chinese, as long as you can provide stability and reasonable life for you they mostly won't care. 

As such Chinese policy is geared towards unity, territorial integrity, stamping out any potential opposition, instilling them with patriotism to view foreigners in a certain way.

The correct answer is b