Which of the following best describes the term 'Resident Alien'?

The term 'Resident Alien' specifically refers to a person who is not a U.S. citizen but is legally residing in the country with permanent residency status, which is obtained through a green card. This status allows an individual to live and work in the United States on a permanent basis.

In this context, the other options do not align with the definition of 'Resident Alien.' A temporary visitor refers to individuals who are in the U.S. for a short period under a non-immigrant visa, lacking permanent residency. A person living in the U.S. on a specific visa may not have the permanent residency status that characterizes a resident alien. Finally, a U.S. citizen is someone who has obtained citizenship, which is a different legal status from being a resident alien. Therefore, describing a resident alien as someone legally residing in the U.S. with a green card accurately captures the essence of the term.