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.
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Question: Category: A CAST OF THOUSANDS 
Clue: It's what you're trying to catch when you're fly-casting

Answer: fish


Question: Category: FILE UNDER "S" 
Clue: Head & Shoulders, Agree, & Pert Plus are leading types of these

Answer: shampoos


Question: Category: COLONIALISM IN AFRICA 
Clue: Millions died from exploitation & overwork in this large Belgian colony

Answer:
the congo