Critical Reasoning

An annually conducted, nationwide survey shows a continuing marked decline in the use of illegal drugs by high school seniors over the last three years.

Which of the following, if true, would provide most support for concluding from the survey results described above that the use of illegal drugs by people below the age of 20 is declining?
(A) Changes in the level of drug use by high school seniors are seldom matched by changes in the level of drug use by other people below the age of 20.
(B) In the past, high school seniors were consistently the population group most likely to use illegal drugs and most likely to use them heavily.
(C) The percentage of high school seniors who use illegal drugs is consistently very similar to the percentage of all people below the age of 20 who use illegal drugs.
(D) The decline revealed by the surveys is the result of drug education programs specifically targeted at those below the age of 20.
(E) The number of those surveyed who admit to having sold illegal drugs has declined even faster than has the number who have used drugs.
OA [spoiler]C but don't understand why D is wrong . Please explain[/spoiler]

jainrahul1985 wrote:An annually conducted, nationwide survey shows a continuing marked decline in the use of illegal drugs by high school seniors over the last three years.

Which of the following, if true, would provide most support for concluding from the survey results described above that the use of illegal drugs by people below the age of 20 is declining?
(A) Changes in the level of drug use by high school seniors are seldom matched by changes in the level of drug use by other people below the age of 20.
(B) In the past, high school seniors were consistently the population group most likely to use illegal drugs and most likely to use them heavily.
(C) The percentage of high school seniors who use illegal drugs is consistently very similar to the percentage of all people below the age of 20 who use illegal drugs.
(D) The decline revealed by the surveys is the result of drug education programs specifically targeted at those below the age of 20.
(E) The number of those surveyed who admit to having sold illegal drugs has declined even faster than has the number who have used drugs.
OA [spoiler]C but don't understand why D is wrong . Please explain[/spoiler]

D - Even if the program was specifically targeted at those below the age of 20, the statement does not support that use of illegal drugs declined among people below 20 years of age, instead the impact was on high school seniors. There is no concrete information, which the question asks, for people below 20 years of age.

IMO C

About D : even if the programs were targeted to high school students below the age of 20 you can not say that it has necessarily brought down the number.