Final answer:
The most effective conclusion to the essay is option c) Outbreaks are becoming more common, but there is still time to act.
Step-by-step explanation:
The most effective conclusion to the essay would be option c) Outbreaks are becoming more common, but there is still time to act. This conclusion effectively summarizes the main idea of the essay, which is that the spread of diseases carried by mosquitoes is increasing, but there is still an opportunity to take action and prevent further outbreaks. It leaves the reader with a sense of urgency and a call to action.
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