Question

What caused the Yuan dynasty to end in the year 1368?
A. The Yellow River flooded
B. The military weakened
C. Kublai Khan died
D. All of the above

Answer 1

I would opt for B, the military weakened, though there were a number of internal problems that caused it.

For why:
A) The flooding of the Yellow River had always been a problem regardless of dynasty.
C) Kublai Khan was long dead by the time the Yuan dynasty fell.

Answer 2

same same
b