The correct answer is: b) secondary and tertiary.
Hydrogen bonds play a crucial role in stabilizing different levels of protein structure. In secondary structure, they form between the backbone atoms in the polypeptide chain, creating common shapes such as alpha helices and beta sheets. However, when we talk about hydrogen bonds specifically involving amino acid side chains, we primarily refer to the tertiary structure.
Tertiary structure arises from interactions among the R groups of the amino acids, including hydrogen bonds, ionic bonds, hydrophobic interactions, and disulfide bonds, all of which contribute to the overall 3D shape of the protein. Quaternary structure, which involves the assembly of multiple polypeptide chains, can also involve hydrogen bonds between these side chains, but the question specifically points to the levels where side chains interact primarily through these bonds, which are most notable in secondary and tertiary structures. Therefore, the best response for this question is ‘b) secondary and tertiary.’