In the Decades Before the Civil War, the Northern States

In the decades before the Civil War, the northern states

A) were unaffected by slavery.
B) refused to follow federal law requiring the return of fugitive slaves.
C) refused to do business with the slave states.
D) financed industrial development with money earned in the trade of cotton produced by slave labor.
E) boycotted all American cotton because it was produced by slave labor.