Why did the "Age of Ingenuity" begin after the Civil War?

This table shows the number of cities in north carolina from 1860 to 1910. which factor was responsible for the change in population from 1860 to 1910? a. the expansion of railroad lines cities grow. b. the growth of farms brought workers into the state. c. the civil war resulted in residents leaving the state. d. the rise of corruption led many residents to leave cities.