The passage addresses which of the following issues related to Glass's use of popular elements in his classical compositions? A. How it is regarded by listeners who prefer rock to the classics B. How it has affected the commercial success of Class's music C. Whether it has contributed to a revival of interest among other composers in using popular elements in their compositions D. Whether it has had a detrimental effect on Glass's reputation as a composer of classical music E. Whether it has caused certain of Glass's works to be derivative in quality