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 consistency, answers should be in all lower cased letters.
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Question: Category: PROVERBS BY INITIALS 
Clue: "A watched P.N.B."

Answer: pot never boils


Question: Category: ON OUR MONEY 
Clue: Appropriately, this landmark is on the reverse of the $5 bill

Answer: the lincoln memorial


Question: Category: ARMY, NAVY, AIR FORCE OR MARINES 
Clue: "The Right Stuff" guy Chuck Yeager after 1947

Answer:
air force