All of the Following Are Justifications for Warrantless Searches of Vehicles

All of the following are justifications for warrantless searches of vehicles at driver checkpoints except ______.

A) drivers are informed of the checkpoints by signs as they approach so they aren't taken by surprise
B) drivers are surprised and subjected to unnecessary delay
C) the stops are brief, and they minimize the stress and fear experienced by motorists
D) police do not single out particular motor vehicles for inspection