The Underground Railroad was a secret system that was run by

a
enslaved workers in fields and in cities.
b
“maroon communities” living in the wilderness.
c
plantation owners and overseers in the South.
d
free African Americans and abolitionists in the North.

The correct answer is D. free African Americans and abolitionists in the North.

Explanation:

the great wall of china worked as a defense for the feudal states of the zhou dynasty to the north. during the warring states period more walls were put up to defend the borders of the different kingdoms. it was semi successful because despite the wall, the mongols eventually conquered china also the great wall provided protection to the economic development and cultural progress, safeguarded the trading routes such as the silk road, and secured transmission of information and transportation. @jayxboof

hi there!

c is your answer

~courtney