题目内容：

There are some new drivers going back to school. Teens who have recently gotten their driver's licenses may be taking the wheel to school this fall. However, parents fear when their teen starts driving. And it turns out that such parental fears are justified, so it's worth reviewing how to keep your teen safe while he or she is behind the wheel.

Motor vehicle crashes are the leading cause of death among US teens. Drivers 16 to 19 years old are at the greatest risk of crashes. In fact, their risk is 4 times greater than that of older drivers. The teens at the greatest risk are those who are male, those carrying other teenage passengers in the car, and those still in their first year of driving. Nearly 50 percent of teen deaths related to automobile crashes happen on Fridays, Saturdays, or Sundays between the hours of 3 pm and midnight.

Why are teens at higher risk of motor vehicle crashes?

Development. Teens haven't completely matured mentally and have greater risk­taking behaviors, possibly because they tend to underestimate the risk associated with a particular behavior. Teens also have a greater tendency to speed and to drive too close to the cars in front of them.

No seatbelts. Teens have the lowest rate of seatbelt use among all driving groups.

Alcohol. A least 25 percent of motor vehicle deaths in teens are related to drinking alcohol.

Technological distractions(分散注意力的事)．Cellphones，texting，MP3 players，and the like can all distract drivers greatly—and who more than teenagers?

Be aware of your teen's driving practices and discuss safe driving habits when opportunities present themselves. Check out the applications and devices now available for restricting your teen's use of technology while driving. Some applications alert you to the danger when your teen is texting while the vehicle is moving. Another device blocks incoming and outgoing texts when the car is running—incoming messages get an automatic reply (eg. “I'm driving right now”), and phone calls go directly to voicemail. You can also get notifications if your teen tries to shut off the program. There are also GPS programs that let you know your new driver's whereabouts at all times. All in all, you can't be too cautious when teaching your teen how to be safe on the road.

1.What factor is least related to the teen drivers' high risks of crashes?

A．Drivers' age.  B．Passengers' sex.

C．Driving experience.  D．Driving time.

2.Teens probably turn away their attention from driving when they are ________.

A．using no seatbelts  B．drinking water

C．carrying passengers  D．answering cellphones

3.According to the passage, which should be prevented during teens' driving?

A．Texting.  B．GPS programs.

C．Automated replies.  D．Voicemail.

4.The author writes the last paragraph in order to ________.

A．offer parents practical suggestions

B．summarize teens' driving practices

C．advocate different driving habits

D．set an example for the teens