Which states were added to the union as part of the Missouri Compromise?

A. Missouri and Nebraska

B. Missouri and Kentucky

O C. Maine and West Virginia

O D. Missouri and Maine

(D)

In an effort to preserve the balance of power in Congress between slave and free states, the Missouri Compromise was passed in 1820 admitting Missouri as a slave state and Maine as a free state.

O D. Missouri and Maine

Explanation:

First, Missouri would be admitted to the union as a slave state, but would be balanced by the admission of Maine, a free state, that had long wanted to be separated from Massachusetts. Second, slavery was to be excluded from all new states in the Louisiana Purchase north of the southern boundary of Missouri.