The maps above demonstrate a major, ongoing problem that emerged early in the Antebellum Period. Which of the following statements best describes this major issue?
a. Slavery was banned above the Missouri Compromise line.
b. Westward expansion forced Northerners to accept limitations on manufacturing.
c. Westward expansion increased the desire to build transcontinental railroads.
d. Westward expansion resulted in increased sectional tensions over the expansion of slavery.