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.
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Question: Category: HISTORIC LASTS 
Clue: In the "thanks a lot, fellas" department, Mongolia was the last country to join this group--August 9, 1945

Answer: the allies


Question: Category: INVENTIONS 
Clue: The delivery system for Ban deodorant, introduced in 1955, was based on this invention, patented in 1938

Answer: ball point pen


Question: Category: PLAGUES & PESTILENCE 
Clue: Having first escaped from a South American research lab in 1957, they became a threat to the U.S. in 1990

Answer:
killer bees