In the bodies of reptiles, some industrial by-products cause elevated hormonal activity. Hormones govern the development of certain body parts, and in reptiles abnormal development of these parts occurs only with elevated hormonal activity. Recently, several alligators with the telltale developmental abnormalities were discovered in a swamp. So, apparently, industrial by-products have entered the swamp' s ecosystem. The reasoning in the argument is most vulnerable to criticism on the grounds that the argument ['fails to say whether reptiles other than alligators were examined for the same developmental abnormalities that were discovered in the alligators', 'fails to address the possibility that industrial by-products were contained in food the alligators ate', 'provides no explanation for developmental abnormalities that do not result from elevated hormonal activity', 'fails to consider whether elevated hormonal activity can result from factors other than the presence of industrial by-products']