The keystone to what henry clay called the american system was a. abolishing slavery. b. a low tariff c. encouraging british competition. d. a high tariff.

d. people are naturally good, and their expressed will is what is best for society

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