It has been said that authors who write in order to give pleasure cannot impart to their readers the truth of their subject matter. That claim cannot be true. If it were, one could determine the truthfulness of a book simply by looking at its sales figures. If the book were very popular, one could reasonably conclude that it gave people pleasure and ttherefore that at least some of what is written in the book is not true. Which one of the following is an assumption required by the argument? ['A book will not give its readers pleasure unless it was intended by its author to have that effect.', 'A book can be popular for reasons other than its ability to give readers pleasure.', 'When people choose to read a book, they generally do not already know whether reading it will give them pleasure.', "In many cases, a book's readers are unconcerned about the truth of the book's contents."]