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: HISTORIC ISLANDS 
Clue: A 900-year-old organization expelled in 1798 was allowed to return to this island in 1998
malta

Category: U.S. PRESIDENTS 
Clue: Washington was the one who added these 4 words to the presidential oath; they're not in the Constitution
\"so help me god\"

Category: AMERICAN MUSIC 
Clue: The brilliance of Anne Brown, a soprano, changed the title of a 1935 opera that was to be called simply this one name

porgy