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. GEOGRAPHY 
Clue: The West Point Military Reservation includes Constitution Island, which lies in this river

SOLUTION: the hudson river

PROBLEM: Category: NATURE STUDY 
Clue: This tall shrub is prized for the reddish dye obtained from its leaves that's used to color hair

SOLUTION: henna

PROBLEM: Category: FLY FISHING 
Clue: These are attached to a fly to help it float; they're also what are "raised" when you get angry

SOLUTION:
hackles