How does variation in amino acid side chains (R groups) contribute to protein diversity?

• A. All side chains are chemically identical; diversity arises only from differences in peptide-bond orientation rather than from R group chemistry.
• B. Different side chains have varied chemical properties (polar, nonpolar, charged), which alter folding, interactions, and thus final protein structure and function.
• C. Side chain variation affects only the primary sequence length, not the folding or function of the protein.
• D. Side chains determine the number of disulfide bonds that convert amino acids into sugars before incorporation into proteins.

Answer: (B)