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: DRAMA 
Clue: Sula & Helena are robotesses in this Karel Capek play

Answer: "r.u.r."


Question: Category: POLITICIANS 
Clue: This champion stock-car racer lost the 1996 race for North Carolina's Secretary of State

Answer: richard petty


Question: Category: ENTERTAINING VILLAINS 
Clue: The costume of this villainous "Batman" character is covered in question marks

Answer:
the riddler