One main reason for the fall of the mongol empire was
a. the spread of diseases brought by europeans.
b. military invasions by muslim armies.
c. a weakened economy due to expensive public works projects.
d. decreased trade with the west after the closing of the silk road.

  A weakened economy due to expensive public works projects.

Explanation:  Large amounts of money spent on public works projects greatly weakened the economy. This, along with the growing discontentment among the Chinese people, led to the fall of the Mongol Empire.

answer; /// (a) and (b) ; /// but i believe the correct answer is ; /apart from fines and jail time, driving under the influence puts the life of the driver and everyone else on the road at risk; (b)

answer; i believe that the correct answer is (decreased)