Answer:
C) Westward expansion and the issue of whether slavery would be allowed in the new territories.
Step-by-step explanation:
There were many social, political and cultural differences between north and the south which led to the civil war. During 1800s the economy of northern states was more industrialised as compared to the south. The farming was the backbone of the southern economy, and it was based on the slave lobar.
The northers believed that slavery was evil and must be abolished. Some of the well known abolitionists were John Brown, Fredrick Douglass and Harriet Tubman. they all tried to convince people about the abolition of slavery. The southern states were afraid of it, because abolition of slavery would have affected their way of life.
Another major issue was the expansion of US toward west.As the new territories in the east were being added to US, it was shifting the power between north and south. Each new state was a battle ground for them. The southern states were afraid the they would loose their rights.