Songwriters get much of the money they earn from their songs from radio airplay. A hit song is played thousands of times, and the songwriter is paid for each play. Only a fraction of songwriters actually achieve a hit, however, and even fewer manage to write several. Writers of hit songs are often asked to write songs for movie sound tracks, but they sometimes decline, because although such songs frequently become hits, their writers receive single up-front payments rather than continued revenues from radio airplay. If the statements above are true, which one of the following must be true? ['Any songwriter who receives revenue from radio airplay has written a hit song.', 'Some songs written for movie sound tracks are played on the radio thousands of times.', 'All songwriters who write songs for movie sound tracks have had their songs played on the radio thousands of times.', 'Some songwriters earn money solely from the radio airplay of their songs.']