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.

Category: THE 19th CENTURY 
Clue: 1853 purchase that brought the contiguous U.S. about up to its present area
the gadsden purchase

Category: LET'S GET SMALL 
Clue: In area, it's the smallest constitutional monarchy in the world
monaco

Category: POTPOURRI 
Clue: Using a 200-year-old technique, a V.A. hospital in Long Beach, Calif. has utilized these fly larvae to treat patients

maggots