Two analogies that relate places/locations to the associated travel mode is given in the form "A : B. C : ?". "A : B" relates place A to travel mode B. Your task is to replace the question mark (?) with the appropriate travel mode for the given place C, following the "A : B" relation.

[Q]: office : car. portland : ?
[A]: car


[Q]: canada : bus. island : ?
[A]: boat


[Q]: spain : airplane. work : ?
[A]:
car