I'm not 100% sure but it could be: Voluntary Exchange takes place between buyers and sellers:
(btw I copied and pasted from the question so I didn't take any content :D)
I think it would be B)International
The Great Wall of China is the longest building on earth with a length of 13,170 miles. Made from a combination of brick, stone, wood and other materials, it was originally constructed primarily to serve as a defence against the nomadic invasions from the north that threatened Chinese states / empires.
The way that Lincoln and Douglas view, disagreement and
facts about slavery is that Lincoln views them that they don’t have the ability
to accept or cope up with the moral standards which was opposite of Douglas
thinks. He also views them that they are also avaricious which Douglas didn't
thought of. While Douglas in the other hand, has the belief that the people’s
choice and having the thought of people who are slaves can back down the
movement of the system of labor.
<span />
