Leon Mailed Out 2,000 Copies of a Questionnaire Aimed at Assessing

Multiple Choice

Leon mailed out 2,000 copies of a questionnaire aimed at assessing people's feelings toward a proposed tax increase. He received 200 completed responses. In drawing conclusions about his findings, he should be most concerned about:

A) interviewer bias.
B) observer bias.
C) social desirability bias.
D) nonresponse bias.