metallicafan wrote:
Amphibian populations are declining in numbers worldwide. Not coincidentally, the earth’s ozone layer has been continuously depleted throughout the last 50 years. Atmospheric ozone blocks UV-B, a type of ultraviolet radiation that is continuously produced by the sun, and which can damage genes. Because amphibians lack hair, hide, or feathers to shield them, they are particularly vulnerable to UV-B radiation. In addition, their gelatinous eggs lack the protection of leathery or hard shells. Thus, the primary cause of the declining amphibian population is the depletion of the ozone layer.
Each of the following, if true, would strengthen the argument EXCEPT:
(A) Of the various types of radiation blocked by atmospheric ozone, UV-B is the only type that can damage genes.
(B) Amphibian populations are declining far more rapidly than are the populations of nonamphibian species whose tissues and eggs have more natural protection from V-B.
(C) Atmospheric ozone has been significantly depleted above all the areas of the world in which amphibian populations are declining.
(D) The natural habitat of amphibians has not become smaller over the past century.
(E) Amphibian populations have declined continuously for the last 50 years.
OFFICIAL EXPLANATION
This question is very difficult than the previous question, in part because one of the wrong answer choices is very attractive.
The conclusion of the argument is a causal statement that the depletion of the ozone layer is the primary cause of the declining amphibian population:
This conclusion is based on the fact that the ozone layer blocks harmful UV-B radiation, which amphibians are vulnerable to in both adult and egg form.
Although the argument mentions UV-B radiation, which may sound impressive, the structure of the reasoning is easy to follow and no knowledge of the radiation is needed. The conclusion is clearly stated and easy to spot due to the indicator “thus.” The question stem is a Strengthen and therefore the four incorrect answers will each strengthen the argument. As with the previous question, look for answers that fit the five causal strengthening answer types discussed earlier.
Answer choice (A): This is the correct answer. The answer fails to shed any light—positive or negative—on the connection between the ozone depletion and the amphibian population decline. Because the argument is concerned with the damage done by UV-B radiation, the fact that UV-B is the only damaging type of radiation blocked by ozone is irrelevant.
Answer choice (B): This answer choice strengthens the argument by showing that when the cause is absent in nonamphibian populations, the effect does not occur (Type C).
Answer choice (C): This answer strengthens the argument by showing that the areas of ozone depletion and amphibian decline match each other, thereby affirming the data used to make the conclusion (Type E).
Answer choice (D): This was the answer most frequently chosen by test takers. This answer choice strengthens the argument by eliminating an alternate cause for the effect (Type A). Had the natural habitat become smaller over the years (from say, human encroachment or climatic change) then that shrinkage would have offered an alternate explanation for the decline in the amphibian population. By eliminating the possibility of habitat shrinkage, the stated cause in the argument is strengthened.
Answer choice (E): This answer strengthens the argument by showing that the decline of the amphibians has mirrored the decline of the ozone layer, thereby affirming the data used to make the conclusion (Type E).
Attachment:
2021-03-29_02-55-44.png [ 21.75 KiB | Viewed 6800 times ]