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: QUOTES 
Clue: 19th century philosopher & poet who advised "Hitch your wagon to a star"

SOLUTION: ralph waldo emerson

PROBLEM: Category: ANIMALS 
Clue: These mollusks, not oysters, are the most common source for freshwater pearls

SOLUTION: mussels

PROBLEM: Category: A NOVEL CATEGORY 
Clue: Your mail carrier may know this was James M. Cain's first novel

SOLUTION:
the postman always rings twice