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 does the speaker focus on in this talk

A.Why we have superstitions.
B.The historical and cultural root of superstitions.
C.Whether superstitions are rational.
D.Who believes in superstitions.