Step 1: Analyze the passage.
The passage discusses Glass's use of popular music in classical compositions, which leads to a return to using such elements in classical music, attempts to elevate rock music to a more classical status, and incorporates elements from rock and classical styles.
Step 2: Review the options.
- (A) Glass's work is not discussed as having specific qualities beyond its influence on music composition.
- (B) The passage suggests that Glass's work is part of a return to popular music in classical composition.
- (C) Glass's incorporation of rock music into his classical works seems like an attempt to elevate rock to a more refined, artistic status.
- (D) The passage discusses Glass's blending of two musical styles, rock and classical.
Step 3: Conclusion.
The correct answers are (B), (C), and (D), as they reflect the core ideas discussed in the passage.
Final Answer:
\[
\boxed{\text{(B), (C), and (D)}}
\]