Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information. A. We cannot definitely say whether or not a massive overkill happened at the end of the Pleistocene, despite what many scientists believe. B. We cannot definitely say whether the massive overkill by the first human inhabitants of the Americas occurred in the middle of the end of the Pleistocene. C. Although it is difficult to know for sure, many scientists believe that the first human inhabitants were responsible for an overkill of mammals at the end of the Pleistocene. D. Many scientists believe that many of the first human inhabitants of the Americas did not survive the climate changes at the end of the Pleistocene.