kanha81 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
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.

Please explain with answers.

relic wrote:The task of this question is to strengthen the argument that the depletion of the ozone has caused the shrinking frog population. The EXCEPT means that four answers will be strengthening ideas, but the correct answer will be something else.

Answer A is irrelevant-- the number of types of radiation that cause gene damage doesn't affect the argument. Thus, this choice is correct.

But I would guess Answer D is a tough one to avoid. However, it does strengthen the argument by rejecting another cause of the declining frog population. Sometimes a strengthening answer will do this, particularly on an argument of cause and effect.