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: ALL ABOUT RIVERS 
Clue: You may be waiting for the Robert E. Lee on a natural one of these raised river banks created by flood waters
answer:
levee


question:
Category: "X" IN THE CITY 
Clue: Famous for temple ruins, this city on the site of Thebes has been called "The World's Greatest Open-Air Museum"
answer:
luxor


question:
Category: WEAPONS OF THE 2nd MILLENNIUM 
Clue: Introduced in World War I, the Mills bomb was actually one of these flung weapons
answer:

a grenade