The statement that best shows how the issue of states’ rights contributed to the onset of the Civil War is:
3. Many Southerners believed the rights of their states were threatened by Northern abolitionists.
This captures the conflict between the South, which sought to protect the institution of slavery as a state right, and the North, where abolitionist sentiments were rising. Southern states felt that their rights to maintain slavery were being directly threatened by Northern political actions and ideologies, leading to heightened tensions and ultimately contributing to the decision of several states to secede from the Union.