单选题
The blues was born on the Mississippi River Delta in the early 1900s. After the Civil War, the slaves were free but life was still not easy. They had to find new work. In the South, work camps were formed. Black people from these camps worked on farms and on building up the Mississippi River banks. During the week the people worked long and hard. They often lived alone, without their families, far from home. On the weekends, the workers got together at picnics or drinking places. Traveling black musicians with guitars entertained them. The musicians sang songs about the difficult life of the Workers. These songs were called the blues. If you have the blues it means you feel very sad. But blues songs were not always sad. Some of them were happy and many of them were funny. Early blues singers often had very interesting names like Blind Lemon Jefferson, Howlin Wolf. Sometimes the blues singers had song contests. Each singer sang new words or a new style of the blues song. They made up the music as they played. In this way they created new music. This is called improvisation (即兴演奏). Later, improvization became a very important part of jazz music. Blues began in the country in the South. As blacks moved into the big cities to work, the blues went with them. There, they sang about life in the cities. W.C. Handy, a black band leader from Memphis made the blues popular all over America. In 1914 he wrote the most famous blues song of all, "The St. Louis Blues./