Final answer:
The 18th Amendment established Prohibition which banned alcohol, and the 21st Amendment later repealed Prohibition, allowing the legal production and consumption of alcohol.
Step-by-step explanation:
The outcome of the 18th Amendment, ratified in 1919, was the establishment of Prohibition, which banned the sale, manufacture, transport, and distribution of alcoholic beverages across the United States. This national Prohibition lasted for 14 years and saw significant opposition and difficulties in enforcement, leading to an increase in organized crime. The 21st Amendment, which was ratified in 1933, brought about the repeal of Prohibition, allowing the legal production and consumption of alcohol to resume.
The correct answer to the student's question regarding the outcome of the 18th Amendment followed by the 21st Amendment is that: b) The prohibition of alcohol was repealed.