GMAT Critical Reasoning (CR) | Re: Herbicides allow cereal crops to be grown very efficiently,

Herbicides allow cereal crops to be grown very efficiently, with virtually no competition for weeds. In Britain, the partridge populations have been steadily decreasing since herbicide use became widespread. Some environmentalists claim that these birds, which live in and around cereal crop fields, are being poisoned by the herbicides. However, tests show no more than trace quantities of herbicides in partridges on herbicide treated land. Therefore, something other than herbicide use must be responsible
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