Hint: After leaving New England when Eli Whitney went to the South in the late 18th century, he invented the machine called Cotton gin. There, he felt the need for an instrument through which the cotton planters could make profits out of its production. He struggled for getting patent rights but finally got it after some years.
The invention of the Cotton gin doubled the yield of the raw cotton year by year, decade by decade. Demand was increased with the other inventions of the Industrial Revolution. It boomed the economy of America as, by that time, America was growing three-quarter of the world’s supply of cotton and its export was mainly to the New England manufacturers where cloth used to be made out of it. However, like any other invention, it also harmed society in the form of the growth of slavery. The labor needed to grow and pick the cotton was enslaved to do more and more production. The number of slave States got more than doubled to 15 in the 1870s, from 6 in the 1790s.
So, the correct answer is Option B.
Note: Because of the growth of Cotton Industries, the slaves’ number, and labor at low cost were also increased throughout the South. Thousands of slaves were imported from Africa at that time. Later on, the growth of slavery caused the civil war in America and consequently, slavery was banned.