The habit many students on today' s campuses have of scribbling in their textbooks is inexcusable. It is harmful to books, aesthetically displeasing, and distracting to readers who buy the textbooks used. Which one of the following, if true, most seriously weakens the argument? ['Many students do not scribble in their textbooks.', 'In most areas, scribbling in textbooks is not illegal.', 'Many recent surveys show that books in public libraries are abused more than textbooks.', 'Most students who buy used textbooks say they are aesthetically indifferent to the scribbling and sometimes find it helpful.']