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.

[EX Q]: mars : spaceship. portland : ?
[EX A]: car

[EX Q]: store : car. airport : ?
[EX A]: train

[EX Q]: theater : car. office : ?
[EX A]:
car