Which of these was NOT a significant effect of the invention of the cotton gin?
A.Southern plantation farmers switched from growing tobacco as their primary cash crop to growing cotton instead.
B.The overall economy strengthened as the north relied even more heavily on southern cotton for its textile mills.
C.The use of slave labor decreased as machines could do the work of the slaves.
D.The number of slaves in the southern states increased as more cotton was planted throughout the south.