As You Read the Results of a Sex Survey Reporting

As you read the results of a sex survey reporting nose biting as the most popular form of foreplay of Canadian university students,you wonder about the accuracy of this report.You note the methods used in this study: it was a web-based survey,conducted on Canadian university campuses,using over-sampling techniques,and it received 77% participation from participants who were randomly invited to participate.What concern might you have regarding this survey?

A) The sample is non-representative of the target population.
B) Most "normal" students were likely too shy to participate.
C) Web-based surveys,like other types of surveys,are subject to self-report errors.
D) More than 50% of the university population is of European descent: over-sampling likely biased the results in favour of their practices.