All of the following are guidelines for developing a marketing research questionnaire except
a. sensitive questions should be asked first.
b. questions should use vocabulary respondents are familiar with.
c. questions should be sequenced appropriately.
d. questions should address only one issue at a time.
d. the layout should be professional and easy to follow.

a.sensitive questions should be asked first.

Explanation:

When conducting marketing research,  the researcher should strive to present the research as professional work. He or she must conduct themselves professionally when presenting the research documents to the respondents. The impression he or she creates in the mind of the respondents may influence the kind response he will get.

Respondents will gauge the professionalism or seriousness of a research study based on the content and flow of questions.  If the first question is sensitive, a majority of respondents will not take the research seriously. The sensitive question may be offensive to some respondents, making them abandon the research. That question may make some respondents uncomfortable and deny the study the seriousness it deserves.

answer; i believe the correct answer is (treasury bills);