Official 9 Passage 1
Question 1 of 14

According to paragraph 1, the theory that people first migrated to the Americas by way of an ice-free corridor was seriously called into question by

A.

paleoecologist Glen MacDonald’s argument that the original migration occurred much later than had previously been believed

B.

the demonstration that certain previously accepted radiocarbon dates were incorrect

C.

evidence that the continental ice began its final retreat much later than had previously been believed

D.

research showing that the ice-free corridor was not as long lasting as had been widely assumed

Paragraph 1 is marked with an arrow

正确答案:B

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