Final answer:
The protein's secondary structure is stabilized by hydrogen bonds between backbone amide protons and carbonyl oxygens, which corresponds to option A. These interactions form the characteristic α-helix and β-pleated sheet structures.
Step-by-step explanation:
The question pertains to the secondary structure of proteins which is characterized by the pattern of hydrogen bonds. The specific interactions that stabilize the secondary structure involve hydrogen bonds between the backbone amide protons and the carbonyl oxygens. This means that the correct answer is A. Backbone amide protons and carbonyl oxygens. In the α-helix structure, these hydrogen bonds occur between an oxygen atom of a carbonyl group and a hydrogen of an amide group four amino acids away along the chain. For the β-pleated sheet, the bonds are formed between the carbonyl and amino groups that are in closer proximity along the backbone. These structures are crucial as they contribute to the overall three-dimensional conformation of the protein which is vital for its function.