单选题：根据内容回答题，It is understood that a ballad is a song that tells

根据内容回答题，It is understood that a ballad is a song that tells a story, but a folk song is not so easily define
D．A balled is a folk song, but a folk song is not a ballad until it tells a story. Folk song, then has included many kinds of musi
C．For example, a sailor’s song of the sea is a folk song. The blues, a type of jazz popular in New Orleans, may be a folk song. In fact, there are folk songs for every job.
“Home on the Range” shows how a popular song may become a folk song. It was first picked up as a folk song in 1910 by John Lomax in San Antonio, Texas. Lomax heard the song from an old man who had been a cook many years before. The song was known all over the Midwest; thought it did not come to national attention until the early 1930s. By 1947 “Home on the Range” was so popular that it became the official state song of Kansas.
A folk song is also a ballad when it . A．tells a story
B．is sung by workers
C．makes the listeners feel sad
D．covers many kinds of music