12. Which of the following events sparked southern states to sec from the Union? A. Abolitionists started a movement B. Kansas was made a free state C. Lincoln was elected U.S. president D. Slavery was outlawed by Lincoln

The election of Abraham Lincoln as U.S. president in 1860 was the key event that ignited the tensions leading southern states to secede from the Union. Lincoln's platform opposed the expansion of slavery into new territories, which alarmed many southerners who viewed this as a direct threat to their way of life and economy, ultimately resulting in their decision to break away. Additionally, the secession of southern states led directly to the outbreak of the Civil War in 1861. As states like South Carolina were the first to secede, they formed the Confederate States of America, further entrenching the division between North and South and escalating the conflict over issues of states' rights and slavery. This historic moment shaped the course of American history and set the stage for profound changes in civil rights and the nation's future.