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.