People flocked to the cities in the late 1800's because during this time factories were booming and there was more opportunity in the cities. Therefore the answer is B.
President Richard Nixon is the only president to resign from the office and was the 37th president of the United States, serving from 1969 to 1974. Vice president Gerald R. Ford of Michigan took the office as the new president to complete the remaining 2 1/2 years of Nixon's term.
