Clouds reflect the majority of incoming infrared radiation back out into space.
a. true
b. false

No, it is generally false that clouds reflect the majority of incoming infrared radiation back out into space, since only roughly 31% of all incoming radiation from the Sun is reflected back into space. 

The best and most correct answer among the choices provided by your question is first choice or letter A.  At its peak, the Mongol Empire included parts of  China, Persia, and Russia.

Mongol invasions and conquests progressed over the next century, until 1300, by which time the vast empire covered much of Asia and Eastern Europe.

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