【正确答案】 D

【答案解析】解析：由“all those giant creatures，the Metgauna of North America were gone．”可知猛犸象消失之前生活在北美。所以答案为D)。

【正确答案】 A

【答案解析】解析：由“One theory is that they were hunted to extinction by humans．”可知教授提到这个是为了提出后面的狩猎理论。所以答案为A)。

【正确答案】 C

【答案解析】解析：由“So I think it is quite likely that those thirteen mammoths in Southern California also died of natural causes，and that the Clovis people simply took advantage of the situation．”教授认为克洛维斯人只是利用了形势，所以答案为C)。