Evolutionary biologists and geologists recognize the "big five" mass extinctions and are actively studying a potential sixth. Which of these describes that potential sixth mass extinction?
A. The extinction that included the dinosaurs
B. The great flood of Noah
C. The current extinctions, caused primarily by human activities
D. The mass extinction that occurred in the Proterozoic, before animal life
E. The end-Carboniferous mass extinction, which affected plants, not animals
Answer: C. The current extinctions, caused primarily by human activities
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