Why did eleven southern states secede from the Union after Lincoln’s election?
选项：

A:Missouri was admitted as a slave state while Main was admitted as a free state.;
B:California was admitted as a free state while Utah and New Mexico were allowed to decide for themselves with regards to slavery.;
C:There were afraid that Lincoln would require newly admitted states to be free.;
D:They were afraid that Lincoln would abolish slavery in the country.