GMAT Verbal Reasoning Practice Test 5

© examsiri.com
Question : 69 of 100
 
Marks: +1, -0
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, casts most doubt on the relevance of the survey results described above for drawing conclusions about illegal drug use in the teen-age population as a whole?
Go to Question: