<span>A human rights agent groups.</span>
Explanation:
The Mason-Dixon line was essentially one of the most used underground 'lines' of railroad to transport slaves to freedom. It was a railroad that, although not important before, became incredibly important over time as it was an essential 'Forgotten' railroad in a way, that was not only able to transport slaves, but had tracks directly into and through both free and slave states.
[I hope this helps:)]
John Tyler became president when president William Henry died in office
Millard Fillmore became president when Zachary Taylor died in 1850
Andrew Jackson became president when Abraham Lincoln was assassinated
Federalist No. 10 continues a theme begun in Federalist No. 9 and is titled "The Utility of the Union as a Safeguard Against Domestic Faction and Insurrection".