The correct option is option A. It destroyed business for the upcountry farmers who could not afford the new invention, and created a larger profit for the lowcountry farmers.
The cotton gin is a machine that separates the cotton fibers from the seeds, and is more productive than the manual process. Before this machine was invented the separation process was very expensive, the farmers and owners needed a lot of slave hand to have a little production. The cotton gin reduced the amont of slave hand, time and price of this process, that leads the growth of cotton plantation in the lowcountry, and they made it their main income.