Which of these was a problem that led to the Civil War?

1. Several problems pushed the North and the South towards war. 2. Slavery was one of them, and it is the problem named first. 3. Economic reasons and states' rights were the other two problems. 4. The Mexican-American War was a separate war the country fought, not a cause of the Civil War. 5. A dispute with Great Britain belongs to the colonial period, when the colonists broke away. 6. A tax on imported tea belongs to that same quarrel with the British, long before the Civil War. _Source: USCIS Civics Flash Cards M-623 (rev. 02/12), public domain, official civics question 74_