A significant difference between the North and the South in the years leading up to the Civil War is described by A. The North favored a protectionist tariff on foreign goods, while the South did not. I hope that this is the answer that you were looking for and it has helped you.
A war of attrition.
World War 1 is an example of this.
WWI tanks were used to lead infantry advances across no mans land (option a ). It was a welcome development, as it was hoped it would help ending the long and casualties provoking trenches type of war.
The answer to your question is B: It explains the organization of the federal government.
