Biologist: Many paleontologists have suggested that the difficulty of adapting to ice ages was responsible for the evolution of the human brain. But this suggestion must be rejected, for most other animal species adapted to ice ages with no evolutionary changes to their brains. The biologist's argument is most vulnerable to criticism on which one of the following grounds? ['It fails to address adequately the possibility that a condition can produce a change in a species even if it does not produce that change in other species.', 'It presumes without warrant that human beings were presented with greater difficulties during ice ages than were individuals of most other species.', 'It takes for granted that, if a condition coincided with the emergence of a certain phenomenon, that condition must have been causally responsible for the phenomenon.', 'It overlooks the possibility that a condition that is needed to produce a change in one species is not needed to produce a similar change in other species.']