Emperor Wen of the Sui Dynasty ended the Northern and Southern Dynasties in 589 A.D. Why is this action considered to be one of his greatest achievements?
A.
It reunified China under a single ruler for the first time in many years.
B.
It allowed the Chinese people to speak the same language.
C.
It signaled the beginning of Chinese expansion into other countries.
D.
It reunited China under a single state sponsored religion.