听力原文： About two percent of the population of the United States is of Asian origin-some

five million people. Chinese, Japanese, and Philippine form. the largest groups. However, there are also significant numbers of Asian-Indians, Pakistanis,' Koreans, and Vietnamese now living in America. As a result of the war in Vietnam, some 350,000 refugees from that country have entered the United States since the early 1970s.

Chinese and Japanese workers were imported into the United States by employers in the late nineteenth and early twentieth centuries. Most of the Chinese settled in California, where they were employed mainly in heavy in dustries, such as mining and railroad construction. They wore faced with in tense prejudice and discrimination, especially from lower-class white people, who saw them as a source of threat to their jobs. The retreat of the Chinese into distinct Chinatowns was not primarily their choice, but was enforced by the hostility they faced. Since Chinese immigration was ended by law in 1882, the Chinese remained largely isolated from the wider society--at least until recently.

Most of the Japanese immigrants also settled in California and the other Pacific states. During World War II, following the attack on Pearl Harbor by Japan, all Japanese-Americans in the United States were made to report to "relocation centers"--which were effectively concentration camps. In spite of the fact that most of the Japanese were American citizens, they were compelled to live in the hastily established camps for the duration of the war.

How many refugees Came from Vietnam since the early 1970s？

A．About 35,000.

B．About 250,000.

C．About 350,000.

D．About 25,000.