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 consistency, answers should be in all lower cased letters.

Q: Category: TWAIN TRACTS 
Clue: A miner bets on his amphibian's leaping ability in "The Celebrated Jumping Frog of" this county

A: calaveras county
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Q: Category: PHRASES OF DEATH 
Clue: Completing 2 tasks with one action is "killing 2" of these "with one stone"

A: birds
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Q: Category: LIFE SCIENCE 
Clue: These disease-causers have a nucleic acid in a protein shell, but not even a single cell

A:
viruses
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