5. Tiger sharks are common in the waters surrounding Tenare Island. Usually tiger sharks feed on smaller sharks, but sometimes they have attacked tourists swimming and surfing at Tenare's beaches. This has hurt Tenare's tourism industry, which is second only to its fishing industry in annual revenues. In order to help the economy, therefore, the mayor of the island has proposed an ongoing program to kill any tiger sharks within a mile of the beaches. Which of the following, if true, most strongly calls into question the likelihood that implementation of the mayor's proposal will have the desired consequence? (A) Even if not all the tiger sharks that come close to the beaches are killed, the existence of the program would reassure tourists. (B) Business owners who depend on tourism are willing to pay most of the cost of implementing the program. (C) Tourists come to Tenare Island for its beaches, even though the island features a number of other tourist attractions. (D) The small sharks on which tiger sharks prey feed on fish that are commercially important to the island's fisheries. (E) Not all tourists who come to Tenare Island enjoy swimming or surfing. 答案是 D 但我不太瞭解 題目是說 tiger sharks 通常以 small sharks 為食 如果市長把海灘附近的 tiger sharks 殺光 那以正常情況而言 small sharks 會增加 這對答案 D 中的 fisheries 應該是有利的 為什麼反而是使市長的政策不能執行的原因? 感謝!! --

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