The correct answer is 1. Innovations in agricultural technology increased cotton production, meaning Southern plantations needed more enslaved workers.
Eli Whitney invented the cotton gin, during the Industrial Revolution, which would change the American economy dramatically. Before this time, picking seeds out of cotton was a long, tedious process. Along with this, the profits generated from cotton were not worth the work that it took. However, this changed when Whitney invented a device that would separate the seeds from the cotton at a rapid pace.
This invention helped spark the popularity of cotton, as it could now generate huge profits thanks to the reduced amount of time it took to remove the seeds from the cotton.