参考答案

正确答案：C
解析：文章第一段第一句"One of the greatest mysteries in the study of Cetacea(aquatic mammals)has always been that the creatures found in the stomachs of toothed whales show no teeth marks"描述了一个难以解释的现象，即在有牙齿的鲸鱼腹内发现的生物身上并没有齿痕；接下来第二句 "Now a University of California at Santa Cruz professor thinks he may have solved the enigma with what he calls the" big bang "theory of cetacean predation"，针对前面的现象提出了一种理论"big bang" theory来予以解释，后面几段一直在围绕这种理论展开介绍和评论，因此选C。