Which factor did not contribute to the development of US imperialism in the late 19th century

During the cold war, which of the following groups of countries would have all been"behind the iron curtain"

The factory system of the early-19th century caused a) a decrease in farm production. b) an increase in rural population. c) an increase in urban population. d) high unemployment in other areas.

Why did the paris peace conference negotiations last over a year?