It is like when you take a medicine you don't need, it becomes useless when you need it because your body can fight it off. So, I would have to say that the pesticides have been used on the bugs so much that they can finally fight it off. I really hoped I helped :D
The answer is D.Angiogenesis
<span>♡♡Hope I helped!!! :)♡♡
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I believe it's B. That would be the best guess
