Which of the following is a type of U.S. territory?

The Northern Mariana Islands is categorized as a type of U.S. territory. Unlike states, U.S. territories have a different legal status and do not have the same level of representation in Congress. The Northern Mariana Islands were established as a commonwealth in political union with the United States, which grants its residents certain rights and responsibilities, while also placing them under U.S. sovereignty.

In contrast, Alaska and Hawaii are both states of the United States and have full statehood benefits, including representation in Congress. Vermont is also a state and, like Alaska and Hawaii, does not fall within the category of U.S. territories. Thus, the Northern Mariana Islands is the only option that correctly represents a U.S. territory.