Final answer:
The Kansas-Nebraska scheme required the repeal of the Missouri Compromise, introducing popular sovereignty in the territories of Kansas and Nebraska as a way to decide on the issue of slavery, overturning previous restrictions. The correct answer is option e.
Step-by-step explanation:
Stephen A. Douglas's plans for deciding the slavery question in the Kansas-Nebraska scheme required the repeal of the Missouri Compromise. The revised Kansas-Nebraska Act, which Douglas introduced, proposed creating two territories - Kansas and Nebraska - and utilized popular sovereignty to decide on the issue of slavery within those territories. This was a shift from the previous policy set by the Missouri Compromise, and it effectively overturned the 36° 30' line that had been established as the boundary for slavery expansion.