Free GMAT Practice Question

Question 1 of 1
ID: GMAT-VR-CR-028
Section: Verbal Reasoning - Critical Reasoning (CR)
Topic: Strengthen
Difficulty level: Medium

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Sediment cores from Lake Anwold contain a thin layer of fine volcanic ash laid down about four thousand years ago. In the sediment immediately above the ash, tree pollen shifts from predominantly oak to predominantly pine within roughly a century. Ash of this composition raises the alkalinity of the soil it settles on, and researchers have proposed that this change in the soil is what drove the forest around the lake from oak to pine.

Which of the following, if true, most strengthens the researchers' proposal?

AThe ash layer is about three times as thick on the western side of Lake Anwold as on the eastern side.

BA mature pine releases many times as much pollen into the air each year as a mature oak of the same size.

CCores from two lakes beyond the ash's reach show oak pollen predominating through that century and later ones.

DThe soil around Lake Anwold today is more acidic than the soil around lakes whose shores carry oak forest.

EThe same ashfall reached forests three hundred kilometres away, where no sediment record of the period has survived.

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