Answer:
Option D is the best answer
Step-by-step explanation:
Option A does not provide a good option because setting up a lab above a restaurant is not a good idea, he cant get participants from the restaurant, people just want to eat and relax in a restaurant not to come and per take in an experiment, option A is not a good fit.
Option B, people will not see her Ph. D as a necessity to per take in the experiment.
Option C, making participant think she is unsure, will definitely make people not serious about the experiment and she wont be able to get best out of the experiment.
Option D, is the best possible answer because a role model or using someone as an example will definitely draw people attention and what ever defiant the example make, the participant will not want to make the same mistake during the experiment. Participant will want to cooperate with the experiment because they have seen a similar figure that did something contrary and the consequence of doing contrary. option D is the best answer to the choice.