Answer:
His research might focus on slavery.
This was the 21st Amendment: the Amendment that repealed the 18th Amendment to the constitution.
The 18th Amendment was the Amendment that introduced the Prohibition for alcoholic drinks; so the 21st Amendment established a permission for the possession of alcoholic drinks.
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The correct answer is letter A. Rome was located on a large river that is why they built aqueducts and sewage systems that eventually paved the way for their great civilization. Water is the main source of agriculture, building, and health for the Romans. Today, a lot of the innovative machines we have are influenced by the Roman Empire.
