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.

[Q]: unlock : key. clamp : ?
[A]: clamp


[Q]: wash : rag. spread : ?
[A]: knife


[Q]: mop : mop. type : ?
[A]:
keyboard