Answer:
Three-fifths compromise, compromise agreement between delegates from the Northern and the Southern states at the United States Constitutional Convention (1787) that three-fifths of the slave population would be counted for determining direct taxation and representation in the House of Representatives.
Abolitionist wanted to end slavery so it should be the second option, hope that helps
The most important event was obviously the American Civil War from 1861-1865. This led to the 14th Amendment which defined a citizen as "any person born or naturalized in the US." The 13th Amendment abolished slavery, and the 15th Amendment prohibits denying the right to vote to someone because of their race.
Other key events include the Louisiana Purchase, the Texas Revolution, The Spanish-American War, the War of 1812, the purchase of Alaska, the Mexican Cession, the Indian Wars, and the California Gold Rush.
Like I said, the right to vote was extended to all male citizens by the 15th Amendment. Women were not given the right to vote until the 19th Amendment was passed in 1920.