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: MEDICINE & HISTORY 
Clue: Montezuma's real revenge: a 1741 British expedition to conquer Mexico was devastated by this "colorful" disease
yellow fever

Category: THE CIVIL WAR 
Clue: A century before the U.S.S. Nautilus, the Confederacy had 2 of these new ships, the Pioneer  & the Hunley
submarines

Category: RELIGION 
Clue: For a Buddhist, this blessed state ends the cycle of death & rebirth

nirvana