Like any historical event, the causes of the Civil War were complicated, but the biggest underlying issue was the disagreement concerning slavery. Some historians have said that economics was the main cause. They argue that the agricultural system of the South was at odds with the industrial, free labor system of the North. The economy of the South revolved around agriculture and slavery. The South was completely committed to a single crop, cotton, which was picked entirely by slave labor. Therefore, virtually all of the labor in the South was slave labor. Many in the northern states felt that slavery was morally wrong, but this was just one cause for concern. The North also worried that slave labor would undermine the position of free white laborers. People in the North worried that the South had intentions to expand slavery, which would make it hard for white laborers to find work.
Still other historians might argue that a rise in sectionalism was the cause of war. The nation seemed to be splitting down social and political lines, becoming two different cultures that embraced very different ideas. These cultures were most strongly divided, however, on the issue of allowing slavery and not allowing slavery. The southern states believed they had the right to practice slavery. To them, ending slavery would mean an end to their culture. Due to these societal differences, the North and South found it difficult to agree on political issues. The two areas of the country grew further apart until it seemed that war was inevitable.

Which of the following choices best describes the opinion of the author of the passage above?

A.
Slavery was the main cause of the Civil War.
B.
The North and South had two different cultures.
C.
People in the North thought slavery was wrong.
D.
Cotton was an important crop in the South.