The Kiffer Forest Preserve, in the northernmost part of the Abbimac Valley, is where most of the bears in the valley reside. During the eight years that the main road through the preserve has been closed the preserve' s bear population has nearly doubled. Thus, the valley' s bear population will increase if the road is kept closed. Which one of the following, if true, most undermines the argument? ["Only some of the increase in the preserve's bear population over the past eight years is due to migration of bears from outside the Abbimac Valley.", 'The bear population in areas of the Abbimac Valley outside the Kiffer Forest Preserve has decreased over the past eight years.', 'The bear population in the Abbimac Valley has remained about the same over the past eight years.', "Only some of the increase in the preserve's bear population over the past eight years is due to migration of bears from other parts of the Abbimac Valley."]