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A positive correlation has been found between the amount of soot

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A positive correlation has been found between the amount of soot  [#permalink]

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19 Jan 2018, 00:29
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A positive correlation has been found between the amount of soot in the atmosphere of cities and the frequency of a certain ailment among those cities' populations. However, the soot itself probably does not cause this ailment, since in cities where there are large amounts of soot in the air, there are usually also high concentrations of many other air pollutants.

Which one of the following statements, if true, most weakens the argument?

(A) In cities where there are high concentrations of many air pollutants but little if any soot in the air, the frequency of the ailment is just as high, on average, as it is in cities where there are large amounts of soot in the air.
(B) If the ailment rarely occurs except in cities in which there are large amounts of soot in the air, then the soot is probably the cause of the ailment.
(C) In each of the cities where there are large amounts of soot in the air but little other air pollution, the frequency of the ailment is at least as high as it is anywhere else.
(D) If high concentrations of many different pollutants in a city's air are correlated with a high frequency of the ailment among that city's population, then it is possible that two or more of those pollutants each causally contributes to the ailment.
(E) In cities in which there are high concentrations of many air pollutants, there are generally also high concentrations of other forms of pollution that are very likely to contribute causally to the ailment.

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A positive correlation has been found between the amount of soot  [#permalink]

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19 Jan 2018, 01:48
Akela wrote:
A positive correlation has been found between the amount of soot in the atmosphere of cities and the frequency of a certain ailment among those cities' populations. However, the soot itself probably does not cause this ailment, since in cities where there are large amounts of soot in the air, there are usually also high concentrations of many other air pollutants.

Which one of the following statements, if true, most weakens the argument?

(A) In cities where there are high concentrations of many air pollutants but little if any soot in the air, the frequency of the ailment is just as high, on average, as it is in cities where there are large amounts of soot in the air.
(B) If the ailment rarely occurs except in cities in which there are large amounts of soot in the air, then the soot is probably the cause of the ailment.
(C) In each of the cities where there are large amounts of soot in the air but little other air pollution, the frequency of the ailment is at least as high as it is anywhere else.
(D) If high concentrations of many different pollutants in a city's air are correlated with a high frequency of the ailment among that city's population, then it is possible that two or more of those pollutants each causally contributes to the ailment.
(E) In cities in which there are high concentrations of many air pollutants, there are generally also high concentrations of other forms of pollution that are very likely to contribute causally to the ailment.

LSAT

The answer is C.

Solving using logic: There are two correlations occurring at once: soot and sickness, and other air pollutants and sickness. The argument is that the second correlation indicates a causal relationship, and not the first one. What would weaken this is being told that the first correlation (soot-sickness) occurred without the first (air pollution): this is exactly what (C) tells us.

Solving by using the answers:
(A) In cities where there are high concentrations of many air pollutants but little if any soot in the air, the frequency of the ailment is just as high, on average, as it is in cities where there are large amounts of soot in the air. this strengthens the argument - air pollution is correlated with sickness, without soot
(B) If the ailment rarely occurs except in cities in which there are large amounts of soot in the air, then the soot is probably the cause of the ailment. There is not information here - it's an "if" sentence, not one that asserts anything
(C) In each of the cities where there are large amounts of soot in the air but little other air pollution, the frequency of the ailment is at least as high as it is anywhere else. so soot is correlated with the sickness without air pollutants - significantly weakens the argument that other air pollutants are causing the ailment
(D) If high concentrations of many different pollutants in a city's air are correlated with a high frequency of the ailment among that city's population, then it is possible that two or more of those pollutants each causally contributes to the ailment. Like B - no information here!
(E) In cities in which there are high concentrations of many air pollutants, there are generally also high concentrations of other forms of pollution that are very likely to contribute causally to the ailment. strengthens the statement that soot is not the cause
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A positive correlation has been found between the amount of soot   [#permalink] 19 Jan 2018, 01:48
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A positive correlation has been found between the amount of soot

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