<span>The situation is one similar to the development of antibiotic resistance. The initial five years of spraying wiped out most of the pests; however, the killing also helped the pesticide-resistant pests to survive and thrive since they had less competition. Over the period of five years, the pesticide resistance became more and more common among the beetles and in the eighth year, almost all of the beetles were resistant to the pesticide. Thus, the answer is D.</span>
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