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

SOLUTION: a valley

PROBLEM: Category: BESTSELLERS 
Clue: "Gettysburg", cowritten by this former House speaker, imagines a Confederate victory at Gettysburg

SOLUTION: newt gingrich

PROBLEM: Category: ANIMALS 
Clue: On a turtle, it's made up of a carapace & plastron

SOLUTION:
shell