What caused the controversy over the addition of Missouri as a state?

Question

a
The vast majority of Americans believed adding Missouri would harm the nation’s economy.
b
Missouri statehood would disrupt the balance between free and slave states in Congress.
c
Fighting between pro- and anti-slavery groups made it difficult for Missouri to elect a state government.
d
Proponents of slavery feared Missouri’s proximity to free states would encourage slaves to revolt.

Answer 1

b
Missouri statehood would disrupt the balance between free and slave states in Congress.