I think it is B. I hope this helps
The presence of north-to-south flowing rivers in the US affected its development by creating a economic bond between the North and the South, which some believe stemmed the onset of the Civil War until the creation of the railroad. Take Chicago, for example. Chicago existed as an agricultural hub where farm goods from the Midwest would go before making their way to larger markets. Before the Civil War, those goods traveled South down the Ohio and Mississippi Rivers and then were sold at New Orleans. This led the Western half of the US to look warily at Civil War because it would directly impact their ability to conduct trade. However, in the 1850s and 60s, Northern manufacturers began building railroads from Northern cities to Chicago, which artificially redirected the flow of farm goods to the East. Now, free from fearing an end of trade, Western politicians were more likely to approve of the Civil War.
it is important because it helps them to get things done faster
