Answer:
The correct answer is C) To create more free states so they could control Congress.
Step-by-step explanation:
Northerners wanted to control Congress because Congress is the branch of government that makes laws for the US. In this case, having more power in Congress would allow Northerners to make laws that would benefit them.
On the other hand, Southerners were fearful that if the North gained more political power in Congress that they would try to outlaw the institution of slavery. After much heated debate, Congress developed the Kansas-Nebraska Act. This allowed citizens of Kansas and Nebraska to vote on whether or not they would allow the institution of slavery in their state.