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: THE PREZ SEZ 
Clue: He once said, "I'm just a politician from Missouri and proud of it"

SOLUTION: harry s. truman

PROBLEM: Category: CHEMISTRY 
Clue: It's the smallest unit of a substance that shows all the chemical properties of that substance

SOLUTION:
molecule