Which of the following is not a reason for the decline of the Mongolian empire

While you didn't provide a lost of possible answers, the correct answer to this question would be, based on the following questions:

A The Mongolians lacked an orderly succession policy.

B The Chinese resented being ruled by a foreigner.

C European imperialism in Asia overcame Mongolian forces.

D Kublai's two failed invasions of Japan emptied the treasury and weakened his forces.

C - European imperialism in Asia overcame Mongolian forces. This is the correct answer because EU imperialism came a few centuries later.