- PowerScore Staff
- Posts: 8950
- Joined: Feb 02, 2011
- Sat Jun 03, 2017 10:19 am
#35647
Complete Question Explanation
Question #4: Strengthen. The correct answer choice is (D)
This stimulus offers a very simple correlation (as pollution occurred, two plant diseases stopped
occurring), and infers a causal relationship between the two elements. Among the possible
approaches to strengthen a proposed causal relationship are eliminating alternate causes, showing
that the cause and effect are both present when either is present or both absent when either is absent,
or demonstrating the cause must have preceded the effect. Look for one of these approaches in the
correct answer choice.
Answer choice (A): Developing a resistance to air pollution is certainly a useful adaptation, but it
does not explain why the diseases disappeared or, more specifically, it does not support the author’s
contention that air pollution eradicated the diseases. Note that the plant diseases were present before
air pollution, so resistance to air pollution cannot also suggest immunity to the diseases themselves.
Answer choice (B): Distinguishing between preventative and curative measures for black spot and
tar spot does not support the claim that air pollution eradicated these diseases. First, we are not told
whether air pollution supposedly cured the diseases, prevented them, or both. Second, this answer
implies that these measures are deliberate interventions and the stimulus does not suggest that air
pollution was introduced to prevent plant disease.
Answer choice (C): If scientists have not determined the effect of air pollution on many plants, we
would be less likely to accept the claim that the effect of air pollution on roses and sycamore trees is
to eliminate black spot and tar spot. This answer choice makes the author’s claim more difficult to
accept.
Answer choice (D): This is the correct answer choice. The author’s cause is air pollution and the
effect is the disappearance of black spot and tar spot. We know from the stimulus that the cause and
effect were simultaneously present; this answer choice suggests that when the cause was removed
(i.e., cities became less polluted), the effect was also absent (i.e., the diseases reappeared).
Answer choice (E): Knowing that only black spot and tar spot disappeared from English cities during
the Industrial Revolution does not support or undermine the author’s claim. Such a fact would only
undermine an explanation whose cause would necessarily eradicate other diseases, as well. Since this
explanation does not address other diseases, limiting the scope of the effect to only those diseases
has no impact on the author’s claim.
Question #4: Strengthen. The correct answer choice is (D)
This stimulus offers a very simple correlation (as pollution occurred, two plant diseases stopped
occurring), and infers a causal relationship between the two elements. Among the possible
approaches to strengthen a proposed causal relationship are eliminating alternate causes, showing
that the cause and effect are both present when either is present or both absent when either is absent,
or demonstrating the cause must have preceded the effect. Look for one of these approaches in the
correct answer choice.
Answer choice (A): Developing a resistance to air pollution is certainly a useful adaptation, but it
does not explain why the diseases disappeared or, more specifically, it does not support the author’s
contention that air pollution eradicated the diseases. Note that the plant diseases were present before
air pollution, so resistance to air pollution cannot also suggest immunity to the diseases themselves.
Answer choice (B): Distinguishing between preventative and curative measures for black spot and
tar spot does not support the claim that air pollution eradicated these diseases. First, we are not told
whether air pollution supposedly cured the diseases, prevented them, or both. Second, this answer
implies that these measures are deliberate interventions and the stimulus does not suggest that air
pollution was introduced to prevent plant disease.
Answer choice (C): If scientists have not determined the effect of air pollution on many plants, we
would be less likely to accept the claim that the effect of air pollution on roses and sycamore trees is
to eliminate black spot and tar spot. This answer choice makes the author’s claim more difficult to
accept.
Answer choice (D): This is the correct answer choice. The author’s cause is air pollution and the
effect is the disappearance of black spot and tar spot. We know from the stimulus that the cause and
effect were simultaneously present; this answer choice suggests that when the cause was removed
(i.e., cities became less polluted), the effect was also absent (i.e., the diseases reappeared).
Answer choice (E): Knowing that only black spot and tar spot disappeared from English cities during
the Industrial Revolution does not support or undermine the author’s claim. Such a fact would only
undermine an explanation whose cause would necessarily eradicate other diseases, as well. Since this
explanation does not address other diseases, limiting the scope of the effect to only those diseases
has no impact on the author’s claim.