The author implies which of the following about the fact that turtles, whales, and dugongs all have flippers? A. It can be explained by the hypothesis that turtles, whales, and dugongs are very closely related. B. It can be explained by the idea of convergent evolution. C. It suggests that turtles, whales, and dugongs evolved in separate parts of the world D. It undermines the view that turtles, whales, and dugongs are all descended from terrestrial ancestors. E. It is the primary difference between turtles, whales, and dugongs, on the one hand, and pinnipeds, on the other.