So, why did Abraham Lincoln gain the support of most of the antislavery forces in the US? Let me tell you: he definitely did NOT cut a deal with the proslavery forces of the south that allowed them to secede. (D is wrong) And contrary to popular belief, he was willing to let slavery be in the South to keep the peace, though he didn't like it. (B is wrong) And the other candidates weren't all in favor of expanding slavery. (A is wrong)
BUT, the others had no problem with LETTING it expand. So, many of the abolitionists rallied behind Lincoln, who wanted to KEEP slavery in the South. He was the closest thing they had to an anti-slavery candidate! C is right!
Answer: the other candidates had no problem with allowing slavery to expand to new states.