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.
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Question: Category: OPERAS BY CONTINENT 
Clue: "Aida "

Answer: africa


Question: Category: 20th CENTURY NOVELS 
Clue: Manfred de Spain appears in "The Town", "The Mansion" & "The Reivers" by this author

Answer: faulkner


Question: Category: AMERICAN POETS & POETRY 
Clue: Although published as a separate volume in 1865, Whitman's "Drum-taps" was later included in this work

Answer:
leaves of grass