Authorities in California required drivers to use their headlights on a certain road during the daytime as well as at night and found that annual accident rates on the road fell 15 percent from the previous level. They concluded that applying the daytime rule statewide would lead to a similar reduction in accidents.
Which of the following, if true, most strengthens the authorities’ argument
A．Because an alternate route became available, the volume of traffic on the test road decreased during the test period.
B．Drivers were informed of the requirement to use their headlights on the test road by means of a series of three conspicuous signs in each direction of travel.
C．Under certain conditions, among them fog and heavy rain, most drivers in California already use their headlights during the daytime.
D．Full-scale application of the daytime rule would cause headlight bulbs to burn out sooner than they currently do and thus to require more frequent replacement.
E．(E) The test road was selected to include a great variety of the sorts of road conditions that drivers in California are likely to encounter.