GMAT Reading Comprehension (RC) | Re: RC - Species Extinction (Short Passage)

The problematic words in choice A are "primarily" and "for survival". Yes, Martin's theory assumes that Paleoindians hunted animals, but that's all you can say. Was it their "primary" food "for survival" ? Perhaps and is reasonable..BUT NOT stated in the passage. Also, the correctness of Martin's theory doesn't depend on it.
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