Gecko lizards are found in any environment where there is an abundant population of gnats. Gnats can survive only in wet climates. Because there are no gecko lizards living here, there must not be an abundant population of gnats here. Consequently, the climate here must not be wet. The reasoning in the argument is flawed in that it ['presumes, without providing justification, that all wet environments contain abundant populations of gnats', 'does not mention whether gecko lizards eat anything besides gnats', 'does not consider whether small populations of gnats can survive in climates that are not wet', 'fails to establish that some gecko lizards could not survive in a dry climate containing only a small population of gnats']