a recent study,published in last填空题

A recent study,published in last week’’s Journal of the American Medical Association,offers a picture of how risky it is to get a lift from a teenage driver.Indeed,a 16-year-old driver with three or more passengers is three times as likely to have a fatal accident as a teenager driving alone.By contrast,the risk of death for drivers between 30 and 59 decreases with each additional passenger.The authors also found that the death rates for teenage drivers increased dramatically after 10 p.m.,and especially after midnight.With passengers in the car,the driver was even more likely to die in a late-night accident.Robert Foss,a scientist at the University of North Carolina Highway Safety Research Center,says the higher death rates for teenage drivers have less to do with"really stupid behavior"than with just a lack of driving experience."The basic issue"he says."is that adults who are responsible for issuing licenses fail to recognize how complex and skilled a task driving is."Both he and the author of the study believe that the way to mitigate the problem is to have states institute so-called graduated licensing systems in which getting a license is a multistage process.A graduated license requires that a teenager first prove himself capable of driving in the presence of an adult followed by a period of driving with night or passenger restrictions before graduating to full driving privileges.Graduated licensing systems have reduced teenage driver crashes according to recent studies.About half of the states now have some sort of graduated licensing system in place,but only l0 of those states have restrictions on passengers.California is the stricter,with a novice driver prohibited from carrying any passenger under 20(without the presence of an adult over 25)for the first six months.A suggested measure to be taken to reduce teenagers’’driving accidents is ______

A．driving in the presence of an adult should be made a rule

B．they should be prohibited from taking on passengers

C．they should not be allowed to drive after l0 p.m.

D．the licensing system should be improved