How did the farm population in the united states change between 1950 and today?
a. it dropped from 10 million to fewer than 3 million people.
b. it dropped from 30 million to just over 6 million people.
c. it dropped from 20 million to fewer than 5 million people.
d. it increased from 10 million to almost 13 million people?

answer: d. geography : )

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