Dr Patal Plans to Administer a Survey About Health-Related Behaviors

Dr. Patal plans to administer a survey about health-related behaviors that put people at risk for HIV infection. He is concerned that his respondents will be reluctant to answer truthfully. He can reduce this potential for biased responding by

A) implying the behavior is common, that "everybody does it."
B) using authority to justify the behavior, such as by starting out "Many doctors now think that …."
C) being casual, such as by using the phrase "Did you happen to …?"
D) doing any of the above.