LSAT 113 – Section 4 – Question 18

LSAT 113 - Section 4 - Question 18

June 2002

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT113 S4 Q18
+LR
Weaken +Weak
Causal Reasoning +CausR
A
2%
151
B
86%
160
C
8%
153
D
2%
151
E
2%
156
127
138
150
 +Easier 145.144 +SubsectionEasier

A plausible explanation of the disappearance of the dinosaurs is what is known as the comet theory. A large enough comet colliding with Earth could have caused a cloud of dust that enshrouded the planet and cooled the climate long enough to result in the dinosaurs’ demise.

Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that the comet theory is a plausible explanation of the dinosaurs’ extinction. This is based on the idea that a collision of a large enough comet into the Earth could have caused a dust cloud that could have cooled the climate long enough to cause the extinction of the dinosaurs.

Notable Assumptions
The author assumes that a large enough comet existed and could have collided with Earth at the time in question. He also assumes that the impact would cause a dust cloud that would cover the planet, and that this would cool the climate long enough to lead to the dinosaurs’ extinction. (The author says that these events “could” happen––we don’t know their likelihood. It could be a very slim possibility.) The author assumes that, even if these events occurred, the cooling caused by the comet is what led to the dinosaurs’ extinction.

A
One of the various schools of paleontology adheres to an explanation for the disappearance of the dinosaurs that is significantly different from the comet theory.
The author is only arguing that the comet theory is plausible; the fact that other theories differ from the comet theory doesn’t weaken the argument. It doesn’t weaken our argument that other plausible explanations may exist.
B
Various species of animals from the same era as the dinosaurs and similar to them in physiology and habitat did not become extinct when the dinosaurs did.
(B) suggests that the extinction of the dinosaurs was driven by some factor that differentiated dinosaurs from other animals with similar habitat and climate needs. If the comet theory was true, animals with similar physiology and habitat to dinosaurs would have gone extinct too.
C
It cannot be determined from a study of dinosaur skeletons whether the animals died from the effects of a dust cloud.
(C) just says that one specific kind of evidence cannot be used. The inability to use skeletons as evidence does not weaken the argument that the comet theory is plausible. (C) makes the inappropriate assumption that skeletons are the only source of information available.
D
Many other animal species from the era of the dinosaurs did not become extinct at the same time the dinosaurs did.
(D) is too broad. The animal species referenced in (D) could have had vastly different requirements for habitat and climate. It makes sense that some animals survived the incident that killed the dinosaurs.
E
The consequences for vegetation and animals of a comet colliding with Earth are not fully understood.
The argument that the comet theory is plausible doesn’t require a full understanding of the impacts of a comet collision on plants and animals, so (E) does not impact the argument.

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LSAT PrepTest 113 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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