The passage supports which of the following statements about the Amery Ice Shelf? A. The Amery Ice Shelf produces only green icebergs. B. The Amery Ice Shelf produces green icebergs because its ice contains high levels of metallic compounds such as copper and iron. C. The Amery Ice Shelf produces green icebergs because the seawater is rich in a particular kind of soluble organic material. D. No green icebergs are found far from the Amery Ice Shelf.