Five years ago, a government grant program helped farmers in the arid Oakhaven region install advanced drip-irrigation systems. These systems deliver water directly to plant roots, reducing the volume of water required per acre by over 40 percent compared to the previously used flood-irrigation methods. Today, even though over 90 percent of Oakhaven's farmers use drip-irrigation and there has been no shift toward more water-intensive crop varieties, the total volume of water drawn annually from the region's aquifers for agricultural use is 15 percent higher than it was five years ago.
Which one of the following, if true, most helps to resolve the apparent discrepancy described above?
- AThe advanced drip-irrigation systems are highly effective at preventing surface evaporation, which was a major source of water loss in traditional flood-irrigation methods.
- BWhile the total volume of water drawn for agriculture increased, agriculture's percentage of the region's overall water consumption decreased due to a rapid expansion in industrial water needs.
- The reduction in water costs per acre achieved through the new drip-irrigation systems allowed many Oakhaven farmers to profitably cultivate large tracts of previously unplanted land.Cevap
- DIn neighboring agricultural regions that did not implement drip-irrigation systems, the total volume of water drawn for agricultural use increased by more than 30 percent over the same five-year period.
- EThe government grant program was heavily oversubscribed, meaning that funds were exhausted quickly and 10 percent of the region's farmers had to continue using less efficient flood irrigation.
Cevap
The correct answer states that the reduction in water costs allowed farmers to cultivate large tracts of previously unplanted land.
The correct answer directly resolves the discrepancy by addressing the mathematical relationship between per-acre usage (a rate) and total usage (an absolute volume). If the cost savings from the more efficient irrigation systems incentivized farmers to plant on significantly more acres of land, the total volume of water drawn would inevitably increase, successfully bridging the two conflicting premises.
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Anahtar Kavram
Resolving a paradox by identifying a missing variable in a rate-versus-volume relationship (often related to the Jevons paradox in economics).