Religion- the Catholic Church use to be head over everything, even the government.
Geothermal plateau. I'm only guessing, but since a lot of places use heat as energy it only makes sense.
Answer:
Primary source
In the study of history as an academic discipline, a primary source is an artifact, document, diary, manuscript, autobiography, recording, or any other source of information that was created at the time under study. It serves as an original source of information about the topic.
Basically, a citizen of the United States is any person who is in possession of the citizenship, which can be acquired by being born on the territory of the US or by being naturalized. The citizens, unlike other legal residents, can choose their representatives in elections.