LSAT Logical Reasoning Question of the Day

Environmental activists who primarily focus on reducing carbon emissions are misguided. There are many environmental issues that should be of great concern, including some that present more serious challenges than carbon emissions. Water pollution, for example, has devastating results on the environment. Activists who primarily focus on carbon emissions apparently do not recognize that water pollution and other issues cause damage to the environment.

Which of the following, if true, most seriously weakens the argument?