C. Classroom lecture delivered by a teacher
Crops from America were grown and sold in Europe and Africa.
<span>To become a citizen of the United States, a person must B. have been born or naturalized in the United States.
If you are born in the US, you are an American citizen. However, that's not the only way to become one - you can also become naturalized, meaning that you either marry an American and get spouse citizenship, or work there for a certain period of time so you can apply for citizenship. These other options (C and D) don't affect your citizenship at all.
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