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.