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: HISTORY 
Clue: In 1720 Victor Amadeus II of Savoy gave Sicily to Austria in exchange for this other large island
sardinia

Category: I HEAR A SYMPHONY 
Clue: Mozart's 38th is called by the name of this city that stood in for Vienna in the filming of "Amadeus"
prague

Category: SIGNS & SYMBOLS 
Clue: Symbols of mystery, they're the mysterious doubles of the people who cast them

shadows