Answer: D. Kublai khan unified china under the Yuan dynasty
Explanation:
Kublai Khan was a grandson of Genghis Khan. Under Genghis Khan, the Mongols had conquered much of Northern China and under Kublai, the North was completely subjugated.
He then turned his attention to the Song dynasty of the south and finally conquered them in 1279. With this China was now completely under his control and he established the Yuan dynasty and became its first emperor.
