There is a difference between beauty and truth. After all, if there were no difference, then the most realistic pieces of art would be the best as well, since the most realistic pieces are the most truthful. But many of the most realistic artworks are not among the best. Which one of the following is an assumption required by the argument? ["An artwork's beauty is inherently subjective and depends on who is viewing it.", 'If an artwork contains nonrealistic elements, then it is not at all truthful.', 'None of the best artworks are realistic.', 'The most beautiful artworks are the best artworks.']