The correct answer is A) That is would be helpful to make a new compromise and stay unified as one nation.
What Lincoln made people see about slavery was that "That is would be helpful to make a new compromise and stay unified as one nation."
That is why Abraham Lincoln said the biblical phrase "a house divided line" during one of his speeches during the Lincoln-Douglass debates when both were trying to be elected Senators for the state of Illinois in 1858. The complete phrase is "A house divided against itself cannot stand."