Dr Shingwauk Designed an Experiment in Which Participants Listened to a Persuasive

Dr. Shingwauk designed an experiment in which participants listened to a persuasive speech delivered either by a very tall person or a person of average height. In addition, the speeches were delivered by people wearing either business clothes or casual clothes. Dr. Shingwauk asked listeners to fill out a survey about impressions of the speaker's credibility. In this study, what is Dr. Shingwauk looking to determine?

A) Does a double-blind procedure lead to greater credibility of speakers, independent of the effects of appearance?
B) Do height and clothing style interact to influence judgements of credibility?
C) Does persuasion interact with any other factors?
D) Does the persuasiveness of the speech depend on the additive effects of height and clothing style?