Please help il mark brainlist what was a major cause of the Civil War?

A ) Northern and Southerns disagreed over the spread of slavery.
B ) Southerns wanted John Browne to receive a fair trail.
C ) Northern and Southerns belonged to different political parties.
D ) Northern's wanted Stephen Douglas to win the election of 1860.

A) Northern and Southerners disagreed over the spread of slavery.

Explanation:

"What led to the outbreak of the bloodiest conflict in the history of North America? A common explanation is that the Civil War was fought over the moral issue of slavery. In fact, it was the economics of slavery and political control of that system that was central to the conflict. A key issue was states' rights."

the answer is catholics

union blockade

explanation:

the union blockade in the american civil war was a naval strategy by the united states to prevent the confederacy from trading.

the blockade was proclaimed by president abraham lincoln in april 1861, and required the monitoring of 3,500 miles (5,600 km) of atlantic and gulf coastline, including 12 major ports, notably new orleans and mobile. those blockade runners fast enough to evade the union navy could only carry a small fraction of the supplies needed. they were operated largely by british citizens, making use of neutral ports such as havana, nassau and bermuda. the union commissioned around 500 ships, which destroyed or captured about 1,500 blockade runners over the course of the war.