单项选择题

Questions 11 to 14 are based on the following passage. At the end of the passage, you will be given 20 seconds to answer the questions.
Now, listen to the passage.

What is the passage mainly about

A.The history of advertisement.
B.The functions of commercials on television.
C.Arguing for the benefits of advertisements.
D.Telling people to be aware of the false advertisements.