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.

the secretary of state, appointed by the president with the advice and consent of the senate, is the president's chief foreign affairs adviser. the secretary carries out the president's foreign policies through the state department and the foreign service of the united states.

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