Dr. belltone recently gave a written survey to 1,000 people about their political beliefs. he found that 42% of people identified themselves as democrats, and 42 % of people identified themselves as republicans, while 16% were "undecided." besides the fact that only a small amount of people responded to the survey, one potential flaw in dr. belltone's study is that those who did respond to the survey may have ?
a. had knowledge of the experiment beforehand.
b. an interest in politics.
c. had their surveys filled out for them.
d. been offered monetary compensation.
e. experienced the mere exposure effect.