The correct answer is Americans learned how to distill alcohol at home.
Prohibition was an era in American history in which the sale, distribution, and transportation of alcohol was illegal. This meant that citizens could not go buy alcohol in the US.
To get their hands on alcohol, individuals learned how to make their own alcohol. This included the concept of moon shining, in which people made liquor using a variety of ingredients. This resulted in a black market in which people made and sold alcohol illegal. Those who sold the alcohol often made significant money, as long as they were not caught by police.
