The Reasoning Behind the Warrantless Search of Automobiles Is That

The reasoning behind the warrantless search of automobiles is that:

A) Because they traverse public roadways,there is no expectation to privacy in one's vehicle
B) Vehicles contain an area too small to require a search warrant
C) Vehicles are moveable,and could drive away before the officer could obtain a warrant
D) Vehicles can have more than one driver,therefore they are not considered under the Fourth Amendment right to be free from unreasonable searches