Which act repealed the Missouri Compromise and allowed the new states of Kansas and Nebraska to choose whether or not to allow slavery?

• A. Ostend Manifesto
• B. Abolition Movement
• C. Kansas-Nebraska Act
• D. Dred Scott Decision

Answer: (C)

The key idea is popular sovereignty—letting the people in a territory decide for themselves whether slavery would be legal there. The Missouri Compromise (1820) drew a line forbidding slavery north of 36°30' in newly organized territories. When the Kansas-Nebraska Act was passed, it changed the rule for those two territories by allowing residents to vote on slavery. This effectively overturned the old ban for Kansas and Nebraska, since slavery could be legal if the settlers chose it. That change helped drive fierce conflict known as Bleeding Kansas as pro-slavery and anti-slavery factions moved to influence the outcome. The other options don’t fit: the Ostend Manifesto aimed to annex Cuba; the Abolition Movement is a broader effort not a specific repeal; the Dred Scott Decision was a Supreme Court ruling, not the law creating Kansas and Nebraska or deciding their slavery status.