Dr. Joseph is testing whether bloodhounds are able to smell people wearing specially designed, airtight bodysuits. In his experiment, a man wearing such a bodysuit hides in a forest, and a bloodhound tries to trail his scent. Dr. Joseph walks along with the bloodhound and monitors its progress. For the results of the experiment to be useful, which of the following should Dr. Joseph do? A. He should give the bloodhound food and water every 30 minutes. B. He should give the man in the bodysuit a compass, so that he can find his way out of the forest. C. He should make certain that the man in the bodysuit gets lost in the forest. D. He should make certain that he does not know the location of the man in the bodysuit.