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

Guam is a U.S. territory, which distinguishes it from the other options mentioned. It is an unincorporated territory of the United States located in the western Pacific Ocean, serving important strategic military and cultural roles. The residents of Guam are U.S. citizens, but they do not have voting representation in Congress, and they cannot vote in presidential elections.

In contrast, Hawaii and Alaska are both states, having achieved statehood and representation equal to other states in the union. Maryland is also a state, located on the East Coast of the U.S. Thus, Guam is the only option that qualifies as a U.S. territory.