Final answer:
The Missouri Compromise admitted Missouri as a slave state and Maine as a free state, establishing the 36°30' parallel as a divide for future slavery decisions within the Louisiana Purchase territory. The correct option is A.
Step-by-step explanation:
The Missouri Compromise was a significant political agreement passed in 1820 that dealt with the expansion of slavery in the United States and the balance of power between slave and free states. As part of the compromise, Missouri was admitted to the Union as a slave state, while Maine was admitted as a free state, maintaining the balance in the Senate.
Furthermore, the compromise introduced the 36°30' parallel as a line dividing future territories into regions where slavery was either allowed or banned—territories north of the 36°30' line, within the land acquired through the Louisiana Purchase, would be free of slavery, with the exception of Missouri.
Speaker of the House Henry Clay played a crucial role in the formation of this compromise. The Missouri Compromise marked a pivotal moment in U.S. history, as it highlighted the deepening divisions over the issue of slavery. The intense debates and legislation surrounding the compromise set the stage for the ongoing national conflict over the spread of slavery, which would ultimately lead to the American Civil War.
Hence, Option A is correct.