The answer is: The cultivation of short-staple cotton became more widespread.
This option is not accurate. While the cotton gin did increase the efficiency of cotton processing, leading to greater production, it did not necessarily cause a drop in the price of cotton due to oversupply. Instead, the demand for cotton, particularly from textile mills in Britain and the northern United States, kept prices relatively stable or even increased due to the higher quality and quantity of cotton available.
This option is incorrect. Contrary to reducing the demand for enslaved labor, the cotton gin actually increased it. The cotton gin made it possible to process cotton much more quickly, which in turn led to a significant expansion of cotton plantations in the Southern United States. This expansion required more labor to plant, cultivate, and harvest the cotton, thereby increasing the demand for enslaved people.
This option is correct. The invention of the cotton gin by Eli Whitney in 1793 made it much easier to separate the seeds from short-staple cotton, which was more difficult to process by hand compared to long-staple cotton. As a result, short-staple cotton, which could be grown in a wider range of climates and soils, became the dominant type of cotton cultivated in the Southern United States. This led to the expansion of cotton farming into new areas and significantly boosted the cotton industry.