B. It reunited northern and southern China in the sixth century.
The Sui Dynasty was a relatively short one, it only lasted from 589 AD to 618 AD. Therefore, A. C. and D. are incorrect because the Dynasty was not in power at those times. So, B is correct because it did reunite northern and southern China with its creation in the 6th century.
In South Carolina, the Regulator movement was an organized effort by backcountry settlers to restore law and order and establish institutions of local government.
The 16th president of the United States was Abraham Lincoln
While you didn't provide any specific era during which any poetry should have came out. I can safely say that the answer you're seeking is A - Haiku.
I know the answer is haiku because the structure you describe; three lines and totals seventeen syllables in the Japanese language is exactly the main characteristic of haikus.