Which one of the following is mentioned in the passage as evidence for the explanation of the dolphin die-off offered in the final paragraph? A. the release of stored brevetoxins from the dolphins' blubber reserves B. the date on which offshore dumping was known to have occurred nearby C. the presence of dumping sites for PCBs in the area D. the synthetic pollutants that were present in the fish eaten by the dolphins E. the effects of PCBs on liver function in dolphins