一道题，我真不知道怎么区分了，大牛帮帮忙吧

ld8822

GWD32—32-34
    The dry mountain ranges of the western United States contain rocks dating back 440 to 510 million years, to the Ordovician period, and teeming with evidence of tropical marine life. This rock record provides clues about  one of the most significant radiations  (periods when existing life-forms gave rise to variations that would eventually evolve into entirely new species) in the history of marine invertebrates. During this radiation the number of marine biological families increased greatly, and these families included species  that would dominate the marine ecosystems of the area for the next 215 million years. Although the radiation spanned tens of millions of years, major changes in many species occurred  during a geologically short time span within the radiation and, furthermore, appear to have occurred worldwide, suggesting that external events were major factors in the radiation. And , in fact, there is evidence of major ecological and geological changes during this period: the sea level dropped drastically and mountain ranges were formed, in this instance, rather than leading to large-scale extinctions, these kinds of environmental changes may have resulted in an enriched pattem of habitats and nutrients, which in turn gave rise to the Ordovician radiation. However, the actual relationship between these environmental factors and the diversification of life forms is not yet fully understood.

Q6. Which of the following best describes the function of last sentence of the passage ?
A.    it points out that the events described in the passage may be atypical
B.    it alludes to the fact that there is disagreement in the scientific community over the importance of the Ordovician radiation
C.    it concludes that the evidence presented in the passage is insufficient to support the proposed hypothesis because it comes from a limited geographic area
D.    it warns the reader against seeing a connection between the biological and geolgic changes described in the passage
E.    it alerts the reader that current knowledge cannot completely explain the relationship suggested by the evidence presented in the passage

c和e把我搞得有点晕，答案是c，能帮忙理一下e为什么不好么？
谢谢阿！！

ld8822

不好意思，答案看串了，版主帮忙删了吧。。。丢人

gwang5

大忽悠啊！