What amendment says all persons born or naturalized in the United States, and subject to the jurisdiction thereof, are U.S. citizens?

What does this answer mean?

The 14th Amendment says that all persons born or naturalized in the United States, and subject to its jurisdiction, are U.S. citizens.

The amendment was ratified on July 9, 1868, three years after the Civil War. Its first sentence defines citizenship: people born or naturalized in the United States and "subject to the jurisdiction thereof" are citizens of the United States and of the state where they live. That settled who counts as a citizen after slavery ended.

The same section protects people in other ways. It says no state may deprive any person of life, liberty, or property without due process of law, or deny any person the equal protection of the laws.

This amendment matters directly to naturalization. The word "naturalized" in its first sentence means that people who become citizens through naturalization are citizens just like people born here. It's also the basis for one of the answers to "How can people become United States citizens?"

At the interview, say "the 14th Amendment."