Free GMAT Practice Question

Question 1 of 1
ID: GMAT-VR-CR-013
Section: Verbal Reasoning - Critical Reasoning (CR)
Topic: Strengthen
Difficulty level: Hard

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Summer algae blooms once clouded Lake Verrin for eight to ten weeks a year; over the past decade they have shortened to three or four weeks. In the same decade the lake's native mussels, which filter fine particles as they feed, recovered from near-absence to dense beds, and farms in the watershed changed their practices. Ines Varga, a limnologist who has studied the lake's shallow bays since before the recovery, argues that the mussels' return shortened the blooms.

Which of the following, if true, most strengthens Varga's argument?

AThe blooms in Lake Verrin have been shorter in each of the last seven summers than in the summer before.

BA dense bed of Lake Verrin's native mussels can filter bloom-forming algae from a large volume of water each day.

CFertiliser runoff from the farms in Lake Verrin's watershed has fallen sharply over the past decade.

DMost of the limnologists who have worked on Lake Verrin accept Varga's account of the mussels' effect.

EAmong the lake's bays, the ones where mussel density rose most are the ones where blooms shortened most.

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