"A house divided against itself cannot stand. I believe this government cannot endure permanently half slave and half free.” -Abraham Lincoln, 1858

According to this quotation, Abraham Lincoln believed that

a. the Southern states should be allowed to secede
b. slavery was immoral and should be abolished immediately
c. sectional differences threatened to destroy the Union
d. to save the nation, the North should compromise with the South on slavery

C. sectional differences threatened to destroy the Union