Answer:
Abraham Lincoln / Believed states should vote to decide on slavery
John Breckenridge / Opposed slavery on moral grounds
Stephen Douglas / Pro-Slavery
John Bell / Silent on the issue of slavery
Explanation:
This were one of the most important elections in the history of US.
It is interesting that Breckenridge who was opposing slavery morally totally changed his views, as he was owning slaves before.
Also, Bell who was from South did not use this question in the elections.
Therefore Lincoln's main opponent was Douglas.
