Free GMAT Practice Question

Question 1 of 1
ID: GMAT-VR-CR-012
Section: Verbal Reasoning - Critical Reasoning (CR)
Topic: Weaken
Difficulty level: Hard

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Six years ago a certain city began requiring every newly constructed office building of more than five storeys to install a cistern that collects rainwater and uses it to flush toilets and water landscaping. Over the six years since, the volume of drinking-quality water the city pipes into its central business district during the summer months has fallen by 22 percent. The city's engineers credit the cistern requirement with the decline.

Which of the following, if true, most seriously undermines the engineers' explanation?

AIn buildings that installed cisterns, summer draw on the mains is about a third lower than in comparable buildings without cisterns.

BBuildings put up before the requirement took effect account for almost all of the district's fall in summer water use.

CMaintaining a cistern costs a building's owner more each year than the drinking-quality water the cistern displaces would cost.

DExtending the requirement to office buildings of three and four storeys would present the city no technical difficulty.

EThe 22 percent figure is a district-wide average, and the reductions recorded at individual buildings vary widely around it.

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