Answer:
C, A, B, D
Step-by-step explanation:
C - The Kansas-Nebraska Act was passed as a bill in 1854 – that allowed territorial colonists to decide if slavery would be permitted within the borders of a new state .
A- The Dred Scott decision was a ruling by the Supreme Court in 1857 – which confirmed that the owners of slaves can take them into western territories.
B - The Lincoln–Douglas debates took place in 1858 – which centered on the issue of slavery in a series of seven debates by Abraham Lincoln and Stephen Douglas.
D- The Harpers Ferry raid happened in 1859 – by John Brown, who tried to instigate revolutions by slaves that require the use of arms.