The protein glutenin is what makes bread dough elastic. The diagram shows a polypeptide of glutenin. Which description matches the structure of glutenin?
- Aquaternary structure because there are both globular and fibrous regions
- Bquaternary structure because there are both spiral and tightly coiled regions
- Csecondary structure because the loose spiral is an $\alpha$-helix
- Dtertiary structure because the different regions form a 3D shape