What is the author's purpose in including the first paragraph of the selection?       once upon a time, music fans had only one way to listen to recorded music.  those lucky enough to own a record player could listen to their favorite tunes in the comfort of their own home.  things have changed since then. people can now carry tiny devices containing thousands of songs.  they can listen to their favorite rock songs wherever they go.  no one can argue that this represents a wonderfully convenient technological achievement.          still, have you ever wondered whether there is a disadvantage to these new technologies?   take mp3s, for example.  mp3s are the digital audio files that many people have on their ipods or home computers.  many people assume that mp3s are superior to other music formats because they take up very little space.          but, for all their usefulness, are mp3s really superior to cds, tapes, and records?   consider for a moment that the average mp3 song file is roughly 11 times smaller than a song file on a cd.  then, think about this:   mp3s are small because they have been  compressed.  file compression is the process of reordering and reducing the information in a file so that it takes up less space. but compression comes at a grave cost.  any recording expert will tell you that music quality is lost during compression.          in fact, lou reed, the famous lead singer of the rock band the velvet underground, has given many interviews about the poor quality of mp3s. reed has often said that these new music files are unlistenable.          so, do not assume that mp3s are superior to cds, tapes, and records.  put it to the test.  for this test, you’ll need a song in mp3 form and the same song in cd form.  listen to each format back to back.  if you listen carefully, you will notice that certain details that can be heard on the cd are missing from the mp3.          prior to the invention of mp3s, recording artists would never have allowed their songs to be compressed.  now, many of us listen to music missing valuable details.  we should not be so foolish as to assume that a new format is better than an old one. a)to show the reader how music formats have changed over time b)to explain why people prefer listening to music on record players c)to suggest that music is more popular than ever before d)to persuade the reader to stop listening to portable devices