Which of the following is NOT a voluntary response sample?
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Choose the correct answer below.
A. A local dentist asks her patients to fill out a questionnaire and mail it back to determine the quality of the care received during an office
visit.
B. Quiz scores from a college level statistics course are analyzed to determine student progress.
C. A radio station asks for call-in responses to a question concerning city recycling.
OD. A survey is taken at a mall by asking passersby if they will fill out the survey.