Which of the following is NOT a way to become a U.S. citizen?

Becoming a U.S. citizen can occur through several pathways, with birth and naturalization being the most common. Birthright citizenship is guaranteed by the 14th Amendment of the U.S. Constitution, allowing anyone born in the United States to become a citizen automatically. Naturalization is the legal process that allows a foreign national to become a U.S. citizen after fulfilling specific requirements, such as residing in the U.S. for a certain period and demonstrating knowledge of U.S. history and government.

A visa application, on the other hand, is a process for individuals seeking permission to enter the U.S. for a temporary duration, typically for purposes such as tourism, work, or study. It does not confer citizenship; instead, it allows individuals to remain in the country legally for a set time under specific conditions.

The option of an Act of Congress usually refers to exceptional cases where legislation may grant citizenship to specific groups or individuals, but this is not a standard method of becoming a U.S. citizen like birth or naturalization. Therefore, a visa application is not a route to citizenship, distinguishing it clearly from the other methods listed.