How did physical features affect mongol expansion​

The geography contributed to the success of the Mongols because the land was flat. The land helped the Mongols because it allowed to see further areas of the land to see enemies.

Explanation:

SOURCE: https://prezi.com/enk-a0-tpjyn/how-did-geography-contribute-to-the-success-of-the-mongols/

the answer is b: an economic crisis throughout the country.