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.
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Question: Category: "D" IN SCIENCE 
Clue: Sharks first inhabited the waters during this period of the Paleozoic era named for an English county

Answer: devonian


Question: Category: ROYALTY 
Clue: Denmark's Queen Margrethe II was born in this "wonderful, wonderful" Danish capital in 1940

Answer: copenhagen


Question: Category: POPULATIONS 
Clue: This tiny principality has the highest population density

Answer:
monaco