Which of the Following Statements About Questionnaire Design Is Incorrect

Which of the following statements about questionnaire design is incorrect?

A) In the introduction section, one should include a general description of the study.
B) One should ask the easy questions first before going to more specific questions.
C) In a given section of the questionnaire, one should mix and match different measurement formats to keep the respondent's interest.
D) Personal questions should be asked at the end of the survey.
E) One should end the survey with a thank you statement.