LSAT 153 – Section 2 – Question 18

LSAT 153 - Section 2 - Question 18

June 2019

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT153 S2 Q18
+LR
Strengthen +Streng
Causal Reasoning +CausR
A
1%
150
B
1%
149
C
60%
163
D
7%
153
E
31%
160
135
154
172
 +Harder 146.684 +SubsectionMedium

Some killer whales eat fish exclusively, but others also eat seals. Different groups of killer whales “chatter” in distinct dialects, and the dialects of seal-eating killer whales are recognizably different from those of killer whales that do not eat seals. Harbor seals use their ability to distinguish between different killer-whale dialects to avoid seal-eating killer whales. Marine biologists hypothesize that young harbor seals start with an aversion to all killer whales but then learn to ignore those that do not eat seals.

Summarize Argument: Phenomenon-Hypothesis
The marine biologists hypothesize that young harbor seals start by avoiding all killer whales, but eventually learn which killer whales eat only fish. Why? Because seal-eating and fish-eating killer whales make chattering noises that sound different from each other, and harbor seals use that difference to tell which killer whales are dangerous.

Notable Assumptions
The marine biologists assume harbor seals avoid seal-eating killer whales because they learn to identify the fish-eating killer whales, and not for any other reason. This means assuming the reverse dynamic—that young seals start with no aversion to killer whales, but acquire an aversion to seal-eating whales—doesn’t happen. It also means assuming the ability to identify seal-eating whales is learned, not purely genetic.

A
Killer whales that eat seals also eat other marine mammals that are similar in size to seals.
This doesn’t affect the argument. It’s equally compatible with the leading alternative hypothesis: that young seals start with no aversion to killer whales, but acquire an aversion to seal-eating whales by observing them eat mammals similar to their own size.
B
Unlike harbor seals, which can hear killer-whale chatter even at great distances, most fish cannot hear that chatter, even close at hand.
This is irrelevant. There’s no indication harbor seals use the behavior of fish to distinguish between seal-eating and fish-eating killer whales.
C
When mature harbor seals first listen to the recorded chatter of killer whales that eat only fish but whose dialect is unfamiliar, the seals rapidly swim away from the sound.
This strengthens the marine biologists’ hypothesis that young seals start with an aversion to all killer whales. It casts doubt on the leading alternative hypothesis: that young seals start with no aversion to killer whales, but learn to be afraid of the seal-eating ones.
D
Young harbor seals show no natural aversion to any seal predators other than killer whales.
If anything, this makes the leading alternative hypothesis more likely. Since it means young seals start with no aversion to other predator species, it suggests the marine biologists’ hypothesis—that young seals start with an aversion to killer whales—would be an anomaly.
E
If a fish-eating killer whale mistakenly attacks a harbor seal, that seal, if it survives, will subsequently avoid all killer whales that chatter in the attacker’s dialect, but other harbor seals will not.
If anything, this makes the leading alternative hypothesis more likely. It implies harbor seals at least sometimes learn to pick out the chattering of dangerous killer whales and acquire an aversion to those whales.

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LSAT PrepTest 153 Explanations

Section 1 - Reading Comprehension

Section 2 - Logical Reasoning

Section 3 - Logical Reasoning

Section 4 - Reading Comprehension

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