题目内容：

    Many teens make risky decisions， such as careless driving or too much drinking． Some of those choices can kill them． Teens may behave in this way because they don't know the possibility of a bad result． Or they may do it because they don't care． In fact， a new study suggests that the second choice is the more likely one．

Wouter van den Bos and Ralph Hertwig are psychologists at the Max Planck Institute for Human Development in Berlin， Germany． They study how people search out information and make decisions according to what they have learned and made an experiment to see if they could solve why teens behave this way． They recruited（招募）105 people， all from 8 to 22 years old． By including different ages， the researchers could test how behavior changes from childhood through to young adulthood．

All played a kind of game． Over and over， they had to choose between taking a guaranteed（确保的）prize of five euros or turning a wheel． The wheel was divided into 10 parts． Some were orange， others blue． If the wheel stopped turning on an orange part， the player won or lost money． This could be between 3 and 32 euros． But if the wheel stopped on a blue part， they got nothing． Each of them played the game 108 times．

① The flve-euro choice was a guaranteed win． It had no risk． However， players who chose to turn the wheel had anywhere from a 10- to 90- percent chance of winning - or losing money． So turning the wheel was a risky choice．

② Teens were more likely to turn the wheel， van den Bos and Hertwig found． The teens didn't care about the lack of information on the risk they were taking． Children and adults， however， avoided those uncertain situations． Instead， they chose the guaranteed reward in the game．

③ "In the teenage years， there is a lot to explore and to learn by exploration，" van den Bos says． Many experiences are new， he says， and teens don't know how they will turn out． "Many of situations are not dangerous and are helpful in becoming an independent adult． So in general， this seems to be good for them，" he says．

④ But， he warns， it's also good to consider whether a behavior may have very harmful results． Where that's the case， he points out， teens should stop to think before they act．

The results are exciting， says Valerie Reyna． A psychologist at Cornell University in Ithaca， N．Y．， she was not involved with the new work． "The most important part of this research is the careful use of lab tasks that separate exploring the unknown from taking risks，" she says．

1.According to the passage， teens prefer to behave in a risky way because ______ ．

A. they don't care much about the result

B. they don't know the possible result

C. they try to avoid uncertain situations

D. they care about the guaranteed prize

2.Which of the following is TRUE about the experiment？ ______

A. It studies how people search out information and make risky decisions．

B. Valerie Reyna was excited because she took part in the experiment．

C. People of different ages were included to see how behavior changes．

D. Teens were able to win money when wheels stopped on orange parts．

3.The researchers think that teens' choices ______ ．

A. are too risky

B. have both good and bad sides

C. do them good

D. have no effect on their life

4.The sentence "Teenagers' risk-taking behavior is meaningful．" should be best placed in ______ ．

A. ① B. ②

C. ③ D. ④