Which of the following describes the primary difference between the normal PrPᶜ protein and the disease version of the protein (PrPˢᶜ).

A) PrPˢᶜ contains additional octapeptide repeats at the N-terminus.
B) PrPˢᶜ contains more beta sheet structure than PrPᶜ.
C) PrPˢᶜ lacks the sugar residues that are attached to PrPᶜ.
D) PrPˢᶜ is not exposed on the surface of the cell.
E) PrPˢᶜ does not bind to copper like PrPᶜ does.