All of the following pre-Civil War conditions contributed to the atmosphere of tension between North and South EXCEPT _________.

The fall of Fort Sumter, mentioned in the first sentence, occurred in April 1861 and was the first battle of the Civil War. This can be gleaned from the context of the first sentence. It was not a “pre-Civil War condition” – It was PART of the war itself. The other options are all mentioned in the passage as events leading up to the Civil War.