Critical Reasoning

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 UV-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.

is it D?

I'm guessing A, since it's the only option that doesn't have "amphibians" in it. The fact that a certain type of UV damages genes (of what? cats? tomatoes?) is not relevant to the whole amphibian - UV correlation.

conclusion

ssmiles08 wrote: the primary cause of the declining amphibian population is the depletion of the ozone layer.

IMO A

D) The natural habitat of amphibians has not become smaller over the past century.
If this is not true this will be provide as another reason for decrease in population

Agree with A - it doesn't strengthen or weaken. It's just extraneous information.

D is incorrect - it strengthens the argument because it eliminates an alternate reason for declining amphibian populations. If their habitat was shrinking because of deforestation or pollution, then that could be a reason for their declining population, and not the depletion of the ozone layer.

OA is A

D is the most suitable option in this case.