Among the many temptations of the digital age, manipulation of photographs has proved particularly troublesome for science. Recently, a journal of cellular biology began using a software tool to examine the digital images submitted along with articles for publication. It discovered that dozens of authors had submitted digital images that had been manipulated in ways that violated the journal' s guidelines. Clearly, scientific fraud is a widespread problem among the authors submitting to that journal. Which one of the following is an assumption required by the argument? ['Scientific fraud is possible in the field of cellular biology only if the research is documented with digital images.', 'Scientific fraud is a widespread problem only among scientists who submit articles to journals of cellular biology.', 'The scientists who submitted manipulated images were aware that the journal used software to examine digital images for evidence of manipulation.', 'Many of the scientists who submitted articles with manipulated images did so in order to misrepresent the information conveyed by those images.']