Which constitutional principle was the main
focus of the north–south conflicts that led to the
civil war?
(1) states rights
(2) due process of law
(3) separation of powers
(4) presidential veto power

The correct answer is 1) States rights.

During the Antebellum period, the Northern and Southern states constantly fought over the issue of states rights. Southerners argued that the federal government was overreaching in their power. An example of this was the creation of laws that dealt with the extension of slavery into new territories gained in the United States. This included laws like the Missouri Compromise, the Compromis of 1850, etc.

i smell fart because the kid next to me smells bad

congress failed to remove johnson. but it did succeed in getting control of efforts to re-build the south following america's civil war. radical republicans wanted to punish the south for starting the war. they also wanted to be sure new governments in the southern states would support the republican party.