How did the expansion of slavery in the mid-nineteenth century lead to the Civil War? Select two correct answers.
a. by increasing sectional tensions over the idea of states' rights
b. by increasing foreign influence over the politics of slave states
c. by inspiring the creation of the republican party that opposed the spread of slavery
d. by decreasing migration to territories west of the mississippi river
e. by limiting the ability of people in free states to learn about the horrors of slavery