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.

Q: Category: LEISURE ACTIVITIES 
Clue: In origami, folding paper down, away from you, is a mountain fold; folding it up toward you is this opposite

A: a valley
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Q: Category: HOW GREAT THOU ART 
Clue: This "mama's boy" answered the art critics in his 1890 book "The Gentle Art of Making Enemies"

A: whistler
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Q: Category: INVENTIONS 
Clue: 2,160 people at a time could ride on this at the 1893 Chicago World's Fair

A:
a ferris wheel
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