You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: ARCHAEOLOGY 
Clue: In 1996 New Mexico wildfires damaged ruins of this tribe the Navajo called "The Ancient Ones"
anasazi

Category: BUMPED FROM THE COVER OF TIME 
Clue: A cover titled "Declining American Birthrate" was canceled in 1974 when this man was pardoned
richard m. nixon

Category: "D" IN SCIENCE 
Clue: About 1 hydrogen atom in 6,500 is this isotope

deuterium