【单选题】

The author refers to the increase in animal bones in the fourth paragraph primarily in order to
A．(A) demonstrate the increase of the availability of grazing mammals during the desiccation of the African landscape

B．(B) suggest a reason why robust proto-humans eventually failed in the competition with Homo for animal prey
C．(C) provide proof that environmental changes did indeed occur around a time of rapid evolution for Homo
D．(D) explain the means by which Homo was able to make use of the appearance of the antelope and gazelle
E．(E) offer evidence that with the desiccation of the African landscape, Homo's diet changed from that of the australopithecine