32. Which of the following statements about fibrous proteins is incorrect? (A) Fibrous proteins usually have good mechanical strength and play a structural role in living organisms. (B) The central rod domain of a-keratin is an a-helix structure flanked by non- helical N- and C- terminal domains. (C) Pairs of right-handed a-helces of a-keratin wrap around each other to form a left-twisted coiled coil. (D) Collagen is an extensible and low glycine content fibrous protein. (E) Silk fibroin is primarily composed of stacked antiparalle! β sheets.