Which of the following was not a cause of the civil war a a belief in states rights B blockading Southern ports C increasing the tariffs placed on foreign textiles d firing on fort Sumter

The answer is D) firing on Fort Sumter. The firing on Fort Sumter was actually an event that marked the beginning of the Civil War, rather than a cause of the war itself. It occurred on April 12-13, 1861, when Confederate forces fired upon Union troops stationed at Fort Sumter in South Carolina.