Answer :
When President Lincoln heard about the creation of the Confederate States of America he threatened the new Confederation of war. The only solution to stop the war was, to Lincoln, the dissolution of the Confederate States and the return of the rebels to the Union. The answer is, therefore: C. He threatened war unless the South returned to the Union.
Actually, the correct answer is B: He refused to accept the secession of states from the Union. I just took the test and it was correct.