求教，新东方逻辑练习题2第九题，请各位大虾不吝赐教

nicklover

题目：The presence of microorganisms that produce a toxin causes seawater to turn brownish red, phenomenon known as a red tide. Sea otters do not feed in areas where clams, their main source of food, have become contaminated with this toxin. According to a proposed explanation of the otters' behavior, the otters sample the clams in a potential feeding areas and can taste any toxin in them.
Which of the following, if true, would most strongly indicate that the hypothesis described in the last sentence of the passage is not correct?
(A) In some of the areas where red tides occur, neither clams nor sea otters are indigenous species.
(B) The presence of sea otters in a given areas has a significant effect on which other marine organisms are to be found in that area.
(C) When seawater in an area unaffected by red tide is artificially dyed brownish red, sea otters do not feed on the clams in that area.
(D) If the clams in a given area are contaminated with toxins, sea ottersmove to other areas in search of food.
(E) Although very small amounts of the toxin produced during a red tide are not harmful, large doses can be fatal to animals the size of sea otters.

答案是选c, 我之前选的是e， 我还是不明白为什么要选c，谢谢~~~~~

freedownload

题干说otter因为尝到clam有毒才不吃，要weaken它：

C说在没有red tide的地方把海水染成红色的，otter也不吃clam，说明otter是看海水的颜色来决定要不要吃clam的。