instruction:
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.
question:
Category: AMERICAN POETRY 
Clue: Walt Whitman called this "the beautiful uncut hair of graves"
answer:
grass


question:
Category: ROYALTY 
Clue: It's the name of today's longest-ruling family in Europe, in power for most of the last 711 years
answer:
grimaldi


question:
Category: HISTORIC AMERICAN PLACES 
Clue: Over 260,000 people have been buried here, starting in 1864
answer:

arlington national cemetery