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: DUEL 
Clue: In English-speaking countries, once a duel was accepted, this person chose the weapons to be used

Answer: the person being challenged


Question: Category: LADS NAMED VLAD 
Clue: In 1929, while working for RCA, this inventor & engineer demonstrated the first practical all-electronic TV

Answer: vladimir zworykin


Question: Category: ELEMENTARY ADVICE 
Clue: Zn before you speak

Answer:
zinc before you speak