- PowerScore Staff
- Posts: 8950
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- Mon Jan 20, 2014 12:00 am
#35652
Complete Question Explanation
Question #8: Weaken. The correct answer choice is (E)
This stimulus, like several others from the past twenty years, addresses theories for the extinction of
the dinosaurs. The obvious inference from the first premise is that the asteroid impact was related to
the extinction of the last dinosaur species. However, the author provides two reasons to doubt this
connection. First, even major asteroid strikes as unlikely to have a worldwide effect. Second, this
purported cause (asteroid strike) is often present historically when the purported effect (extinction)
is not present. To weaken the author’s argument, we must strengthen the initial causal association
between this strike and the extinction of the last dinosaur species.
Answer choice (A): If (A) is true, then the author is likely correct to claim that the catastrophe was
not responsible for most of the dinosaur extinctions during the time period. After all, extinctions
which occure well before the impact cannot be the result of the impact.
Answer choice (B): While this fact is useful in determining how large and forceful the impact at
Chicxulub may have been, it does not weaken the author’s argument. The author’s first premise
describes any major asteroid impact as having primarily local effects and a six mile crater is certainly
the result of a major impact. Thus, no matter how large the asteroid or how forceful its impact, we
have no reason to believe that it could have affected dinosaurs across the planet.
Answer choice (C): This is the first likely Contender, as it establishes a connection between the
cause and effect. Closer examination, however, reveals that the author does not reject any connection
between dinosaur extinction and the asteroid impact; indeed, the author acknowledges that asteroid
strikes kill many organisms in or near the region of impact, as this answer suggests. Even if this
answer is true, it does not indicate that most of the dinosaur extinctions around the time of the impact
were caused by the asteroid and therefore does not weaken the argument.
Answer choice (D): Since the author has already shown this strike to be an implausible explanation
for global dinosaur extinction, ruling out similar strikes does nothing to make it more likely that this
strike was responsible for most of this extinctions. This answer choice rules out the possibility that
the extinctions were due to a series of similar asteroid strikes, but does not undermine the possibility
that some alternative cause was responsible for killing whichever species were not wiped out by the
Chicxulub impact.
Answer choice (E): This is the correct answer choice. The author has effectively limited the
probable scope of even a major asteroid strike to in or near the region of impact. This means that
the asteroid itself is unlikely to have killed dinosaurs around the world. However, it does not ensure
that the impact did not cause most of the extinctions which occurred at that time. If (E) is correct
and most of the dinosaurs alive at the time were local to the impact, then the strike could have had a
limited scope and still been responsible to most of the extinctions.
Question #8: Weaken. The correct answer choice is (E)
This stimulus, like several others from the past twenty years, addresses theories for the extinction of
the dinosaurs. The obvious inference from the first premise is that the asteroid impact was related to
the extinction of the last dinosaur species. However, the author provides two reasons to doubt this
connection. First, even major asteroid strikes as unlikely to have a worldwide effect. Second, this
purported cause (asteroid strike) is often present historically when the purported effect (extinction)
is not present. To weaken the author’s argument, we must strengthen the initial causal association
between this strike and the extinction of the last dinosaur species.
Answer choice (A): If (A) is true, then the author is likely correct to claim that the catastrophe was
not responsible for most of the dinosaur extinctions during the time period. After all, extinctions
which occure well before the impact cannot be the result of the impact.
Answer choice (B): While this fact is useful in determining how large and forceful the impact at
Chicxulub may have been, it does not weaken the author’s argument. The author’s first premise
describes any major asteroid impact as having primarily local effects and a six mile crater is certainly
the result of a major impact. Thus, no matter how large the asteroid or how forceful its impact, we
have no reason to believe that it could have affected dinosaurs across the planet.
Answer choice (C): This is the first likely Contender, as it establishes a connection between the
cause and effect. Closer examination, however, reveals that the author does not reject any connection
between dinosaur extinction and the asteroid impact; indeed, the author acknowledges that asteroid
strikes kill many organisms in or near the region of impact, as this answer suggests. Even if this
answer is true, it does not indicate that most of the dinosaur extinctions around the time of the impact
were caused by the asteroid and therefore does not weaken the argument.
Answer choice (D): Since the author has already shown this strike to be an implausible explanation
for global dinosaur extinction, ruling out similar strikes does nothing to make it more likely that this
strike was responsible for most of this extinctions. This answer choice rules out the possibility that
the extinctions were due to a series of similar asteroid strikes, but does not undermine the possibility
that some alternative cause was responsible for killing whichever species were not wiped out by the
Chicxulub impact.
Answer choice (E): This is the correct answer choice. The author has effectively limited the
probable scope of even a major asteroid strike to in or near the region of impact. This means that
the asteroid itself is unlikely to have killed dinosaurs around the world. However, it does not ensure
that the impact did not cause most of the extinctions which occurred at that time. If (E) is correct
and most of the dinosaurs alive at the time were local to the impact, then the strike could have had a
limited scope and still been responsible to most of the extinctions.
