In the United States, how do classical and popular music differ?

a. Classical music is mostly heard on recordings, whereas popular music is most often experienced live.
b. Classical music audiences tend to be young, whereas popular music audiences tend to be old.
c. Classical concerts often take place outdoors, whereas popular performances take place in formal concert halls.
d. Classical concerts tend to play the music of a small number of composers, whereas popular music has much more diversity.

d