Need answer asap- 15 points + brainliest what was the effect of the invention of the cotton gin on the united states in the first half of the nineteenth century? a. the focus of economic activity in the south shifted from agriculture to industrial production. b. the south became more dependent on slavery, deepening the differences between the south and the north. c. industrialists from the north migrated to the south in large numbers to set up textile mills and shipping firms. d. large numbers of plantation workers in the south lost their jobs and moved north in search of jobs.