What was an irony about the cotton gin?

a. the device did not need gin to work properly.

b. most slaves did not know how to work it.

c. slaves did not really need it.

d. cotton demand actually decreased.

e. the inventor of the machine was from the north?

Eli Whitney, the inventor of the cotton gin was from the North. This isn't a full irony because the textile mills in the north did benefit greatly from cheap cotton that the cotton gin made possible because it cut the processing cost of the cotton down to almost nothing.