It has been claimed that television networks should provide equal time for the presentation of opposing views whenever a television program concerns scientific issues -- such as those raised by the claims of environmentalists -- about which people disagree. However, although an obligation to provide equal time does arise in the case of any program concerning social issues, it does so because social issues almost always have important political implications and seldom can definitely be settled on the basis of available evidence. If a program concerns scientific issues, that program gives rise to no such equal time obligation. Which one of the following, if true, most seriously weakens the argument? ['Some social issues could be definitely settled on the basis of evidence if the opposing sides would give all the available evidence a fair hearing.', 'Many scientific issues have important political implications and cannot be definitely settled on the basis of the available evidence.', 'No scientific issues raised by the claims of environmentalists have important political implications.', 'There are often more than two opposing views on an issue that cannot be definitely settled on the basis of available evidence.']