The correct answer is B. the population of slaves in the South increases.
The invention of the cotton gin by Eli Whitney in 1793 significantly increased the efficiency of cotton processing. This led to a dramatic rise in cotton production, which in turn fueled the demand for slave labor to plant, tend, and harvest the cotton fields. As cotton became a highly profitable cash crop, the need for slaves to work on plantations increased, which ultimately contributed to the expansion of slavery in the Southern United States.