At which point do you think civil war might have been averted?

Analyzing American history today tells us that the only way to avoid the Civil War (From 1861 to 1865) was if Slavery was made legal in all the Northern and Southern States which actually was not possible as Abraham Lincoln would have not agreed to it. In another words it could not have been averted which is a popular believe in many historians. 

the answer is a) high entry costs