
Passage: On August 10, 2012, South Korean President Lee Myung-bak visited Dokdo (known as Takeshima in Japan), which has a sovereignty dispute with Japan. The results of public opinion surveys show that after Lee Myung-bak's visit to Dokdo, his support rate rose from 25.7% to 34.7%.
Question: If the results of the survey are true, which of the followings must be true?
A. A.More South Koreans support Lee Myung-bak's visit to Dokdo than do not.
B. B.After Lee Myung-bak's visit to Dokdo, some people who did not support him have now turned to him.
C. C.South Koreans who supported Lee Myung-bak before August 10, 2012 continue to support him.
D. D.Lee Myung-bak's visit to Dokdo is the reason for his rising of the support rate.
Answer: