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: BORDERS 
Clue: Argentina's border with this country is 3,200 miles long, about the same as its coastline

SOLUTION: chile

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: A LITTLE OF EVERYTHING 
Clue: Measuring over 14 feet long with two faint images, it's been preserved at a royal chapel in Italy since 1578

SOLUTION:
the shroud of turin