The hemocyanin of arthropods and molluscs differ from the hemoglobin of mammals in that

A) the oxygen dissociation curve for hemocyanin is linear.
B) hemocyanin carries appreciably more carbon dioxide.
C) hemocyanin has protein coupled to copper rather than iron.
D) the protein of hemocyanin is not bound to metal.
E) hemocyanin includes cyanic acid.