In my opinion, the correct answer is a) Affliction. One of the few dictionary meanings of the word "scourge" is lash or whip, but it is also some grave mischief, misfortune, infliction, disaster. The word is often used in the context of catastrophes such as pestilence, war, devastation. In its other meaning (whip, lash), it is usually used in the context of punishment or chastisement, which doesn't really fit into this statement of Abraham Lincoln. He didn't see the war as a punishment but as a catastrophe.
