LSAT 143 – Section 4 – Question 04

LSAT 143 - Section 4 - Question 04

June 2015

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Question
QuickView		 Type Tags Answer
Choices		 Curve Question
Difficulty		 Psg/Game/S
Difficulty		 Explanation
PT143 S4 Q04
+LR
+Exp
Strengthen +Streng
Causal Reasoning +CausR
A
1%
149
B
0%
150
C
0%
147
D
96%
164
E
2%
155
125
134
142
 +Easiest 146.108 +SubsectionMedium

In polluted industrial English cities during the Industrial Revolution, two plant diseases—black spot, which infects roses, and tar spot, which infects sycamore trees—disappeared. It is likely that air pollution eradicated these diseases.

Summarize Argument: Phenomenon-Hypothesis
The author hypothesizes that air pollution most likely eradicated the plant diseases black spot and tar spot. This is based on the observation that those two diseases disappeared in industrial English cities during the Industrial Revolution—places where there was high air pollution.

Notable Assumptions
The author assumes that the observed correlation between air pollution in English cities and the disappearance of the two plant diseases is due to the former causing the latter. This means that the author also assumes there was no alternative cause of the diseases’ disappearance.

A
Scientists theorize that some plants can develop a resistance to air pollution.
Like (C), this is irrelevant because we don’t care about plants’ reaction to pollution, only two specific plant diseases.
B
Certain measures help prevent infection by black spot and tar spot, but once infection occurs, it is very difficult to eliminate.
This is too vague to be useful, because it doesn’t tell us why these diseases are difficult to eliminate or what might succeed in eliminating them.
C
For many plant species, scientists have not determined the effects of air pollution.
Like (A), this is irrelevant because the author’s hypothesis is about plant diseases, not plants themselves. How plants are affected by air pollution is totally outside the argument’s domain.
D
Black spot and tar spot returned when the air in the cities became less polluted.
This strengthens the author’s argument by reinforcing the relationship between air pollution and the two plant diseases. If the diseases come back when pollution decreases, that backs up the hypothesis of a causal relationship.
E
Black spot and tar spot were the only plant diseases that disappeared in any English cities during the Industrial Revolution.
This is irrelevant, because we’re only concerned with these two diseases, and this tell us nothing new about them. We simply don’t care about what happened to other plant diseases.

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LSAT PrepTest 143 Explanations

Section 1 - Logical Reasoning

Section 2 - Reading Comprehension

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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