What problem did the missouri compromise solve?

a.
southern states wanted to admit a free state.

b.
northerners did not want more slave states than free states.

c.
the missouri territory had to choose to be a free state or a slave state before joining the union.

d.
missouri wanted to join the union as a free state.

I am pretty positive that the answer is B, but I could be wrong. I think it is right because if only Missouri would have been added in as a slave state, then the balance of slave and free states would be destroyed. Therefore, the Missouri compromise allowed for two more states to be added, one of which was Missouri and the other was Maine. Missouri was admitted as a slave state and Maine was admitted as a free state to maintain the balance.

The Missouri Compromise of 1820 was an effort by the U.S. Senate and House of Representatives to maintain a balance of power between the slave holding states and free states.