Rumored declines in automobile-industry revenues are exaggerated. It is true that automobile manufacturers' share of the industry' s revenues fell from 65 percent two years ago to 50 percent today, but over the same period suppliers of automobile parts had their share increase from 15 percent to 20 percent and service companies (for example, distributors, dealers, and repairers) had their share increase from 20 percent to 30 percent. Which one of the following best indicates why the statistics given above provide by themselves no evidence for the conclusion they are intended to support? ['No explanation is given for why the revenue shares of different sectors of the industry changed.', "No matter what changes the automobile industry's overall revenues undergo, the total of all shares of these revenues must be 100 percent.", "The possibility is left open that the statistics for manufacturers' share of revenues come from a different source than the other statistics.", "Manufacturers and parts companies depend for their revenue on dealers' success in selling cars."]