The author's objection to the second hypothesis discussed in the passage is most applicable to which one of the following explanations concerning the extinction of the dinosaurs? A. The extinction of the dinosaurs was the result of gradual changes in the composition of the Earth's atmosphere that occurred over millions of years. B. The dinosaurs became extinct when their food supply was disrupted following the emergence of mammals. C. The dinosaurs succumbed to the new, colder environment brought about by a buildup of volcanic ash in the atmosphere. D. After massively overpopulation the planet, dinosaurs disappeared due to widespread starvation and the rapid spread of disease. E. After radical climatic changes resulted from the impact of a comet, dinosaurs disappeared from the Earth.