Which of the following establishes an employee's identity to legally work in the United States?

A U.S. Passport serves as a primary document that establishes an individual's identity and eligibility to work in the United States. It is an official government-issued identification that confirms both citizenship and identity, making it highly authoritative for employment verification purposes.

While other documents like a Social Security card, Certificate of Naturalization, and Driver's License can also provide verification of identity, they may not all confirm the right to work in the same definitive manner. A Social Security card does not indicate citizenship status, and a Driver's License, while it can establish identity, does not inherently verify immigration status or employment eligibility. The Certificate of Naturalization, while indicating that an individual is a naturalized citizen, does not serve the same identification purpose in the context of work eligibility as a passport does. Therefore, the U.S. Passport is the most comprehensive document for confirming both identity and legal work status within the United States.