Scientists evaluating the Cretaceous mass extinctions have concluded that: A. many factors, including climate change, volcanic activity, and an extraterrestrial impact, may have played a role. B. only an extraterrestrial impact could have caused such a big extinction event. C. climate change could not have been involved in producing the extinctions. D. there is no evidence of increased volcanic activity during the late Cretaceous. E. ecological factors such as disease and competition probably caused the dinosaurs to go extinct.