Two analogies that relate actions to the tools used to perform the action is given in the form "A : B. C : ?". "A : B" relates action A to tool B. Your task is to replace the question mark (?) with the appropriate tool for the given action C, following the "A : B" relation.
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Question: wash : washcloth. dig : ?

Answer: shovel


Question: unlock : key. mop : ?

Answer: mop


Question: dig : shovel. mop : ?

Answer:
mop