What was the main reason railroad lines expanded in the south during the late 1800s

natural resources

Explanation:

Mainly Natural resources to help out the Nothern part of america and they transferred things such as metals, coal, and other materials, also was a good source of transportation. The rail roads were also used by the south and north to transport ammunition and resources such as food clothing tents and barricades in the Civil War Era.

the answer is a. laws were enacted in the aftermath of the plot to make it harder to free slaves,increasing sectionalism