TOEFL Reading: ETS-TOEFL阅读机经 - JQ75RWZ5FP1Z153YL$

In paragraph 2, why does the author mention "the Harif point?" A. To support the idea that the Younger Dryas required Natufians to hunt in new ways B. To illustrate how humans had begun to protect their settlements during the Younger Dryas C. To contrast the settled lifestyle of villages with the transient lifestyle of hunter-gathers D. To explain the process by which ancient people invented arrowheads