Which of the following best describes the function of the highlighted sentence? A. It explains why observers who were looking at the meteor would be the only ones who could hear the sounds made as it went overhead. B. It explains why the witnesses' claims could not be verified by scientific experts. C. It shows that Keay's hypothesis provides the correct explanation of the sounds heard by observers of the meteor. D. It suggests that Keay's hypothesis is capable of explaining an important aspect of the witnesses' observations. E. It suggests that Keay's hypothesis is able to explain how observers can see a fast-moving meteor.