The correct answer is C, as the status of slavery during the time of the Dred Scott case was creating tension between the North and the South.
Unable to buy his freedom, in 1846 Dredd Scott filed a lawsuit in the Circuit Court of St. Louis. Scott remained on solid legal ground, since Missouri's precedent dating back to 1824 held that slaves released through a prolonged residence in a free state would remain free when brought back to Missouri. The doctrine was known as "Once free, always free." Scott and his wife had resided for two years in free states and free territories, and their eldest daughter had been born on the Mississippi River, between a free state and a free territory.
The case Scott v. Emerson was tried in 1847 in the federal state court of St. Louis. Samuel M. Bay tried the case in court. The verdict was against Scott, since the testimony that established that his property by Mrs. Emerson was declared by hearsay. However, the judge called for a new trial, which was finally held in January 1850. This time, direct evidence was presented that Emerson owned Scott, and the jury ruled in favor of Scott's release.
Irene Emerson appealed. In 1852, the Supreme Court of Missouri annulled the lower court's ruling, arguing that the growing anti-slavery sentiment in the free states made it no longer necessary for Missouri to adhere to the laws of free states. In doing so, the court annulled 28 years of precedent in Missouri. Judge Hamilton R. Gamble, who was later appointed governor of the state, disagreed strongly with the majority decision and wrote a dissenting opinion.
In 1853, Scott again sued, this time under federal law. Irene Emerson had moved to Massachusetts, and Scott had been transferred to Irene Emerson's brother, John F. A. Sanford. Because Sanford was a citizen of New York, while Scott would be a citizen of Missouri if he were free, the federal courts had diversity jurisdiction over the case. After losing again in federal district court, they appealed to the Supreme Court of the United States in Dred Scott v. Sandford. (The name is spelled "Sandford" in the court's decision due to an administrative error).
The Supreme Court ruled that African-Americans had no right to freedom or citizenship. Because they were not citizens, they did not have the legal capacity to file a lawsuit in federal court. Because slaves were private property, Congress did not have the power to regulate slavery in the territories and could not revoke the rights of a slave owner according to the place where he lived. This decision nullified the essence of the Missouri Compromise, which divided the territories into free or slave jurisdictions. Speaking on behalf of the majority, Taney ruled that because Scott simply considered himself the private property of his owners, he was subject to the Fifth Amendment to the United States Constitution, which prohibits taking ownership of his owner "without due process".
Scott's decision increased tensions between pro-slave and antislavery factions in both the north and the south, further pushing the country to the brink of civil war. Finally, the Fourteenth Amendment to the Constitution resolved the problem of black citizenship through Section 1 of that Amendment: "All persons born or naturalized in the United States, and subject to its jurisdiction, are citizens of the United States and of the State where they reside".