I think it's D. I'm not positive though.
The use of mechanized farming techniques is well suited to geographic areas that c. have large expanses of flat land. Regions such as the Canadian Prairies is a large expanse of flat land and as such easily supports mechanization in planting crops such as wheat. Mechanization in agriculture would be hampered in areas that experience frequent flooding as equipment could get stuck in mud or suffer other water damage.
Prior to the existence of the nation-state, Europe was comprised of several multi ethnic empires, the largest and most powerful of which was the Holy Roman Empire. Territory changed hands often. Many times, this took place because of marriage or as a result of war.
C. increased job opportunities :)
