单选题 What is the "big bang" theory of cetacean predation? ______.

A、 Sixty-eight species of odontocetes use sound to locate their victims
B、 Toothed whales use sound as weapons
C、 Whales and humans have vestigial structures
D、 Whale teeth, once sharp, have become somewhat short and uneven

【正确答案】 A

【答案解析】第二段具体说明"big bang" theory的内容，其中第二句"He points out that all 68 species of odontocetes (a sub-order that includes dolphins) ues sound to locate their victims"，对照选项A。