Câu hỏi:

Part 2. Questions 66 – 75 (2.0 points - 0.2/ each)

Read the passage below and choose the best answer to each question

          Jazz is an improvisational form of music that originated in the southern United States after the Civil War. Although its origins and history are somewhat vague, we know that it began as the musical expression of black people who had formerly been slaves, combining hymns, spirituals, and traditional work songs into something quite new. The style was a blend of the rhythms brought to America by the Africans who were imported as slave labor and the popular music of the era that featured the ragtime piano. The term jazz itself is of obscure and possible nonmusical origin, but it was first used to describe this particular kind of musical expression in about 1915. A jazz band commonly includes four to twelve musicians with a relatively large proportion of the group in the rhythm section. Customarily, there are a drummer, a bass player, and a pianist. Often there is also a banjo player or guitarist. In traditional jazz, the clarinet, trumpet, and trombone carry the melody. In more modern jazz, the saxophone, violin, and flute may also be included in the melody section. Some jazz bands employ a blues singer. Most jazz is premised on the principle that an almost infinite number of variations can accommodate themselves to a progression of chords that can be repeated indefinitely to feature an improvisation by solo instruments or vocalists. For example, while the trumpet plays the melody, the clarinet might embellish and invent compatible melodies around the original theme. Such improvisation is a test of the jazz musician's skill and is referred to as tone color. Jazz first became popular outside the United States in the 1920s when jazz bands began to record, distribute, and even export their recordings to Europe. Since jazz is improvisational, it does not exist in the form of printed scores, and recorded performances were and still are the best way of preserving the music. A very basic library of recorded jazz would include work by such classic artists as Jelly Roll Morton, Louis Armstrong, Duke Ellington, Count Basie, and Billie Holiday. Theirs is probably America's most unique and most important contribution to the musical world, although there are a few contemporary artists who are keeping the tradition alive.

Which of the following is the main topic of the passage?