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: THE BRITISH ISLES 
Clue: This island group that lies just north of the Scottish mainland was known to classical writers as the Orcades

Answer: the orkney islands


Question: Category: HAY IS 
Clue: ...Animal fodder made from cereal grasses like this one, also the first name of the current treasury secretary

Answer: timothy


Question: Category: DOUBLE S 
Clue: This tropical root is used to make tapioca

Answer:
cassava