Critic: Rock music is musically bankrupt and socially destructive, but at least the album covers of rock LPs from the 1960s and 1970s often featured innovative visual art. But now, since the success of digital music has almost ended the production of LPs, rock music has nothing going for it. Which one of the following is an assumption on which the critic's argument relies? ['In the 1960s and 1970s, only rock LPs featured innovative album cover art.', 'Digital music is not distributed with accompanying innovative visual art.', 'Although very few LPs are produced today, most of these are rock LPs.', 'The LPs being produced today have innovative album cover art.']