Answer:
C. Missouri joined the United States as a slave state, and Maine joined as a free state.
Explanation:
A little while earlier before it was passed, in February 1819, Representative James Tallmadge Jr., who was a Jeffersonian republican from New York, had submitted two amendments to Missouri's request for statehood, which included restrictions on slavery. The South — being a mostly slave-dependent economy — objected to ANY bill that imposed federal restrictions on slavery. They believed that this was a state issue, as settled by the Constitution.
However, with the Senate evenly split at the opening of the debates, both sections possessing 11 states each, the admission of Missouri as a slave state would give the South an advantage. Northern critics, including Federalists and Democratic-Republicans, objected to the expansion of slavery into the Louisiana Purchase territory (which was brought in 1803) on the Constitutional inequalities of the three-fifths rule (passed in 1787), which conferred Southern representation in the federal government derived from a state's slave population. Jeffersonian Republicans in the North ardently maintained that a strict interpretation of the Constitution required that Congress act to limit the spread of slavery on egalitarian grounds.
When free-soil Maine offered its petition for statehood, the Senate quickly linked the Maine and Missouri bills, making Maine admission a condition for Missouri entering the Union as a slave state. Maine would have to enter as a free state, which it did on March 15, 1820.
Senator Jesse B. Thomas of Illinois added a compromise proviso that excluded slavery from all remaining lands of the Louisiana Purchase north of the 36° 30' parallel. The combined measures passed the Senate, only to be voted down in the House by Northern representatives who held out for a free Missouri.
Speaker of the House Henry Clay of Kentucky, in a desperate bid to break the deadlock, divided the Senate bills, and thus the Missouri Compromise was born. However, it was incredibly controversial, and many worried that worried that the country had become lawfully divided along sectional lines. It was eventually repealed by the Kansas-Nebraska Act in 1854, and was declared unconstitutional in Dred Scott vs. Sanford (1857), both of which increased tensions over slavery and contributed to the start of the Civil War in 1861.
I know that was long, but I wanted to explain everything in detail. But anyway, I hope this helps! ^v^
