Before the Civil War, plantations in the South produced millions of pounds of cotton. Between 1820 and 1860, about 75 percent of the world's cotton supply was produced in the Southern states. Most of the cotton was sold to textile mills in Great Britain, usually for large profits.

The passage supports the conclusion that before the Civil War,

A.
cotton was an important part of the South's basic tax structure.

B.
cotton provided most workers in the South with a good income.

C.
cotton was an extremely important part of the South's economy.

D.
cotton sales allowed the South to develop an industrial economy.