How did the u. s. feel about expanding the country in the late 1800s, and how was this different from what most european countries were doing ?

The focus was on expansionism, the United States took little part in foreign affairs for much of the 1800s. Committed to the policy of isolationism, the U.S. declined to intervene in an independence movement in Poland when asked to do so by foreign leaders. 

just finished this it is b. centrifugal force

if i am correct the answer is going to be a) the federal program of reconstruction ended.