Answer:
The correct answer will be -tertiary structure
Explanation:
Proteins are one of the important bio-molecules which perform various roles depending on their structures. Proteins form four structures: primary (linear), secondary (folded), tertiary (highly folded) and the Quaternary structures.
The structure of the protein which can be marked by the spiral turns which are held together by hydrogen bonds formed between the C=O and N-H groups stabilize the compounds is known as the tertiary structure. This structure also contains other covalent bonds like C=O and N-H groups phobic interactions.
Thus, the tertiary structure is the correct answer.