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

The process of becoming a U.S. citizen includes several established pathways, and one of these pathways does not represent a direct route to citizenship. Natural birth in the U.S. or natural citizenship through U.S. citizen parents are both recognized avenues under the 14th Amendment and laws governing citizenship. Furthermore, naturalization provides a structured process for lawful permanent residents to become U.S. citizens after meeting specific criteria, such as residency and moral character requirements.

In contrast, simply residing in the U.S. for ten years does not automatically grant citizenship. While continuous residency can be a part of the naturalization process, it is insufficient by itself; individuals must apply for citizenship and meet additional requirements. Thus, residency for ten years lacks the legal framework that defines the established methods of acquiring U.S. citizenship, making it the correct choice for the question at hand.