单项选择题

Questions 18 to 20 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.

Which of the following statements is NOT true

A.About five million of the population of the United States is of Asian origins.
B.Most of the Chinese were employed in heavy industries when they first came to the United States.
C.Chinese people retreated into Chinatowns out of their own choice.
D.Chinese immigration was ended by law in 1882.