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: U.S. RIVERS 
Clue: The Falls of Saint Anthony stop this mighty river from being navigable north of St. Paul, Minnesota

SOLUTION: the mississippi

PROBLEM: Category: FAMOUS FOLKS 
Clue: Actress whose autobiography is named for her most famous role, "Baby Doll"

SOLUTION: carroll baker

PROBLEM: Category: CLASSICAL MYTHOLOGY 
Clue: Achilles died after one of these weapons wounded him in the heel

SOLUTION:
an arrow