In a recent study, researchers collected current prices for the 300 most common pharmaceutical drugs from the leading wholesalers specializing in bulk sales. It was found that these prices average 60 to 80 percent below the suggested wholesale prices listed for the same drugs in the current annual edition of a widely used, independently published pharmaceutical price guidebook. Each of the following, if true, would help to explain the situation described above EXCEPT: ['Suggested wholesale prices for the most common pharmaceutical drugs tend to be less than those for less common pharmaceutical drugs.', 'Wholesale prices for pharmaceutical drugs often fluctuate dramatically from one month to the next.', 'The prices suggested by the independently published pharmaceutical price guidebook are for sales of relatively small quantities of pharmaceutical drugs to individual doctors.', "A price war wherein pharmaceutical drug wholesalers tried to undercut each others' prices began shortly before the study was conducted."]