A TOEFL Reading passage on evolutionary biology mentions a study showing that giraffes with longer necks survived droughts better than short-necked individuals. The question asks: "Why does the author mention this study?" The correct answer would be:
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A
To explain why giraffes evolved in the African savanna
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B
To illustrate how natural selection favored a specific physical trait under environmental pressure
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C
To argue that drought is the greatest threat to giraffe populations
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D
To compare giraffes to other animals that evolved long necks