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hy903

PASSAGE 56
*Although numbers of animals in a given region mayfluctuate from year to year, the fluctuations are oftentemporary and, over long periods, trivial. Scientistshave advanced three theories of population control to
5) account for this relative constancy.The first theory attributes a relatively constant popu-lation to periodic climatic catastrophes that decimatepopulations with such frequency as to prevent themfrom exceeding some particular limit. In the case of
10) small organisms with short life cycles, climatic changesneed not be catastrophic: normal seasonal changes inphotoperiod
daily amount of sunlight), for example,can govern population growth. This theory---thedensity-independent view---asserts that climatic factors
15) exert the same regulatory effect on population regard-less of the number of individuals in a region.A second theory argues that population growth isprimarily density-dependent---that is, the rate ofgrowth of a population in a region decreases as the
20) number of animals increases. The mechanisms thatmanage regulation may vary. For example, as numbersincrease, the food supply would probably diminish,which would increase mortality. In addition, as Lotkaand Volterra have shown, predators can find prey more
25) easily in high-density populations. Other regulatorsinclude physiological control mechanisms: for example.Christian and Davis have demonstrated how thecrowding that results from a rise in numbers may bringabout hormonal changes in the pituitary and adrenal
30) glands that in turn may regulate population by loweringsexual activity and inhibiting sexual maturation. Thereis evidence that these effects may persist for threegenerations in the absence of the original provocation.One challenge for density-dependent theorists is to
35) develop models that would allow the precise predictionof the effects of crowding.
*A third theory, proposed by Wynne-Edwards andtermed "epideictic," argues that organisms have evolveda "code"in the form of social or epideictic behavior
40) displays, such as winter-roosting aggregations or groupvocalizing; such codes provide organisms with infor-mation on population size in a region so that they can,if necessary, exercise reproductive restraint. However,wynne-Edwards' theory, linking animal social behavior
45) and population control, has been challenged, with somejustification, by several studies.

5.     The challenge posed to the Wynne-Edwards-theory by several studies is regarded by the author with

(A) complete indifference

(B) qualified acceptance

(C) skeptical amusement

(D) perplexed astonishment（B）

(E) agitated dismay

为什么呢？好像文中没有明显提到作者态度的词。

对这种态度题好像老是错，有什么方法可以提高吗？

请赐教！

hy903

顶顶，请大家帮忙啊！