The correct answer is B) whether the South had the right to secede.
The issue in which Lincoln and Davis most strongly disagreed was whether the South had the right to secede.
The major difference between Abraham Lincoln and Jefferson Davis was for the Confederacy. Lincoln was the President of the Union and Davis became the President of the Confederated States. Davis believed that the states had the right to leave the Union because the states were sovereign and had the legal arguments to do so. Lincoln completely opposed to David's arguments.
The other options of the question were A) whether the South had seceded for a reason. C) whether slavery would continue to exist in the South. D) whether the North and the South would go to war.