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.

[Q]: Category: ON THE GO 
Clue: John Ericsson, who built a steam locomotive in England in 1829, built this famous Civil War steam-powered ship
[A]: the monitor


[Q]: Category: FREUD 
Clue: The one great question Freud said he could not answer was "What does" one of these "want?"
[A]: a woman


[Q]: Category: INGREDIENTS IN THE MACBETH WITCHES' CAULDRON 
Clue: "Wool of" one of these flyers
[A]:
bat