Answer:
The answer is D)The cotton gin was invented
Step-by-step explanation:
The cotton gin was invented by Eli Whitney at the end of the 18th century, in 1793. It constituted a huge change in the American cotton industry. However, it led to the increase of slavery because the owners were in need of workforce. During these times, the number of slaves rose from around 700,000 in 1790 to around 3.2 million in 1850 .