Question ID:PT53 S3 Q6 Passage:Ornithologist: This bird species is widely thought to subsist primarily on vegetation, but my research shows that this belief is erroneous. While concealed in a well-camouflaged blind, I have observed hundreds of these birds every morning over a period of months, and I estimate that over half of what they ate consisted of insects and other animal food sources. Stem:The reasoning in the ornithologist's argument is most vulnerable to criticism on the grounds that the argument Correct Answer Choice:DChoice A:assumes, without providing justification, that the feeding behavior of the birds observed was not affected by the ornithologist's act of observation Choice B:fails to specify the nature of the animal food sources, other than insects, that were consumed by the birds Choice C:adopts a widespread belief about the birds' feeding habits without considering the evidence that led to the belief Choice D:neglects the possibility that the birds have different patterns of food consumption during different parts of the day and night Choice E:fails to consider the possibility that the birds' diet has changed since the earlier belief about their diet was formed