What term is used for the quaternary structure of a collagen molecule?
- Apolypeptides that form an $b1$-helix, which are held together by covalent bonds
- Bpolypeptides that form a double helix, which are held together by hydrogen bonds
- Cfour polypeptides that are held together by covalent bonds, which form a helix
- Dthree polypeptides that form helix structures, which are held together by hydrogen and covalent bonds