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: SALAD DRESSING 
Clue: This national-named dressing often made with ketchup is found in deli sandwiches

A: russian dressing
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Q: Category: SUCH GOOD CHEMISTRY 
Clue: A U.S. nuclear weapon using this element, Co, has been termed a doomsday device, as it would wipe out life on Earth

A: cobalt
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Q: Category: MOVIEMAKING 
Clue: The length of movies was once described in numbers of these circular holders for film

A:
reels
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