100分求一道简单英语阅读理解题目,要求答案注明理由

100分求一道简单英语阅读理解题目,要求答案注明理由
41.
Today ,as in every other day of the year ,more than 3000 U.S.adolescents（青年人） will smoke their first cigarette on their way to becoming regular smokers as adults.During their lifetime,it can be expected that of these 3000 about 23 will be murdered,30 will die in traffic accidents,and nearly 750 will be killed by a smoking-related disease.The number of deaths attributed to cigarette smoking outweighs all other factors,whether voluntary or involuntary,as a cause of death.
Since the late 1970s,when daily smoking among high school seniors reached 30 percents,smoking rates among youth have declined.While the decline is impressive（印象深刻的）,several important issues must be raised.
First,in the past several years,smoking rates among youth have declined very little.Second,in the late 1970s,smoking among male high school seniors exceeded that among female by nearly 10 percent.The statistic is reversing.Third ,several recent studies have indicate high school dropouts have excessively high smoking rates,as much as 75 percent .
Finally,though significant declines in adolescent smoking have occurred in the past decade,no definite reasons for the decline exist.Within this context,the National Cancer Institute (NCI) began its current effort to determine the most effective measures to reduce smoking levels among youth.
According to the author,the deaths among youth are mainly caused by _____.
单选题
A.traffic accidents
B.smoking-related disease
C.murder
D.all of these
Every day there are over _____high school students who will become regular smoker.
单选题
A.75
B.23
C.30
D.3000
By "dropout" the author means______.
单选题
A.students who failed the examination
B.students who left school
C.students who lost their way
D.students who were driven out of school
The reason for declining adolescent smoking is that ________.
单选题
A.NCI has taken effective measures
B.smoking is prevented among high school seniors
C.there are many smokers who have died of cancer
D.none of these
What is implied but not stated by the author is that ________.
单选题
A.smoking rates among youth have declined very little
B.there are now more female than male smokers among high school seniors
C.high smoking rates are due to the increase in wealth
D.smoking at high school are from low socio-economic backgrounds