Reading comprehension about CDs

[Linh Bui Hoang]

Please read this following short passage:

Compact discs (CDs) have revolutionized the music industry with their surprisingly realistic sound. The six-inch discs look like thin plastic sandwiches with aluminum in the center. They have digitally recorded material that is read by laser beams, so the sound has none of the cracking of vinyl records. CDs are also virtually indestructible, and they are lighter and smaller than conventional records (LPs). Since their introduction, CDs have become more affordable and widely available. In fact, they are now sold in electronics and video stores that haven’t formally carried records or cassettes.

Question: The main appeal of CDs is their..
A. price B. availability C. sound D. size

I think the answer is C, noticing the phrase "their surprisingly realistic sound" in the first sentence. But my teacher says that the answer is D. What do you think about this?

[Jamie (K)]

You're right. The article dwells quite a while on the sound produced by the CDs and how it is produced. It makes only one mention of their size. The answer D makes no sense, because the article mentions cassettes, which were even smaller than CDs, but did not produce comparable sound.