Free LSAT Practice Question

Question 1 of 1
ID: LSAT-LR-205
Section: Logical Reasoning
Topic: Weaken the Argument
Difficulty level: Medium

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Astronomical society secretary: Three years ago the town replaced its street lamps with lamps that throw no light above the horizontal. Our meter, taken at ten on every clear night from the roof, points straight up, and it gives a reading a third of a magnitude darker than before the lamps went in. The town has altered nothing else about its lighting. So it is the lamps that have darkened our sky.

Which one of the following, if true, most weakens the secretary's argument?

AThe retail park at the town's edge lit its yard through the night until last winter, and now switches off at midnight.

BTwo members of the society take the meter turn about, and one makes the same clear sky on a night a tenth of a magnitude darker than the other.

CThe society takes its meter readings only on clear moonless nights, of which the town now has fewer.

DThe society's members say the sky over the town looks darker on a clear night than it did, and they can see stars a magnitude fainter.

EA meter of that pattern reads about a tenth of a magnitude darker for every year its sensor has been in service, whatever the sky over it is doing on the night.

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