Enforcement of local speed limits through police monitoring has proven unsuccessful in the town of Ardane. In many nearby towns, speed humps (raised areas of pavement placed across residential streets, about 300 feet apart) have reduced traffic speeds on residential streets by 20 to 25 percent. In order to reduce traffic speed and thereby enhance safety residential neighborhoods, Ardane's transportation commission plans to install multiple speed humps in those neighborhoods.
Which of the following, if true, identifies a potentially serious drawback to the plan for installing speed humps in Ardane?
【选项】On residential streets without speed humps, many vehicles travel at speeds more than 25 percent above the posted speed limit.