Let's start by going through the passage as a whole. The author begins by telling us that there are many distinct dialects of Chinese and that some linguists argue that a new dialect has evolved in the United States: "Chinatown Chinese."
The author then presents the two claims which support the argument that a new dialect has evolved:
(1) Chinatown Chinese is so different from any other dialect used in China that Chinese immigrants may have a difficult time communicating with Chinese Americans in San Francisco.
(2) Regardless of one's traditional dialect, one can effectively communicate with Chinese Americans in San Francisco if one understands the uniquely Chinese-American terminologies.
The author then presents us with evidence that contradicts both claims.
The first claim is not quite true because Chinese Americans and newcomers from China can communicate relatively easily as long as they speak the same traditional Chinese dialect. Changes in vocabulary are largely related to places and things not encountered in China. As the author writes in lines 27 to 29, "the new vocabulary has supplemented, but not supplanted, the traditional language in the traditional dialects."
The second claim is a "misleading oversimplification" for two reasons. First, although many Chinese-Americans have become familiar with Cantonese (the most common dialect spoken in the U.S.), this is not the same thing as sharing a unique Chinatown dialect. Second, dialects can differ greatly; therefore, even shared terms will not ensure mutual understanding as the remainder of the language can differ greatly.
In this way, the author contradicts the linguists' claims supporting their argument that Chinatown Chinese is a new dialect. This is restated by answer choice (C), making it the correct answer.
Answer choice (A) is incorrect because the fact that Cantonese speakers can understand Chinatown Chinese does not necessarily mean that the latter is not a new dialect. We know nothing about the level of understanding that speakers of other traditional dialects have of Chinatown Chinese. Additionally, this is not the main point of the author's argument; rather, this is one fact which supports the author's contradiction of the linguists' second claim.
Answer choice (B) is incorrect because the author does not simply describe the linguists' arguments; rather, they use the passage to introduce these arguments and then present evidence to contradict them.
Answer choice (D) is incorrect because neither the author nor the linguists make this claim.
Answer choice (E) is incorrect because the author tells us that some linguists believe that Chinatown Chinese is a distinct new dialect.
Hope this is helpful! Please let us know if you have any further questions.
