Considering the available options, the change that occurred in North Carolina's economy after the Civil War is that "the textile industry grew in Piedmont."
Following the end of the American Civil war in 1865, North Carolina diversified their economic attention to textile mills and cigarette production.
By the late 19th century, the economy of North Carolina was based on the cotton mills in which the majority of the industries were located in Piedmont.
Later, North Carolina delve into the aviation industry and military tools and equipment during World War I period.
Hence, in this case, it is concluded that the correct answer is option C. "the textile industry grew in Piedmont."
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