The best answer to this question is clearly D. All of the above statements are definitely true.
Of course, there is no way to objectively define “long, destructive and violent,” but the Civil War certainly seems to fit this description. It lasted about four years and led to the deaths of hundreds of thousands of people. Campaigns like Sherman’s “March to the Sea” devastated large areas of the country. The South was, of course, defeated. It was transformed by this defeat and by Reconstruction. Its slave system was destroyed and its society and economy were altered.
For these reasons, it is clear that D is the best answer of those given.