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: AKA 
Clue: Helen Louise Leonard got this stage name from Tony Pastor and her diamonds, we assume, from Jim Brady
[A]: lillian russell


[Q]: Category: DECEMBER 1st 
Clue: 1959: 12 countries including the U.S. & the U.S.S.R. sign a treaty to keep this continent a scientific preserve
[A]: antarctica


[Q]: Category: HORSEMEN 
Clue: From a word meaning "adventurer" or "vagabond", they were the Russian army's elite horsemen
[A]:
cossacks