单项选择题

Questions 15 to 17 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions. Now, listen to the passage.
What is the talk mainly about

A.The types of instruments used in bebop music.
B.The social setting in which bebop music developed.
C.How two styles of jazz music influenced each other.
D.The influence of bebop music on the United States economy during the 1940’s.