Peptide bonds link amino acids in proteins

Steps:

• Recall that a peptide bond forms between the carboxyl group of one amino acid and the amino group of another, creating -CO-NH- linkage.
• Examine each option for presence of this bond.
• Identify molecules: assume A is a simple sugar, B is a dipeptide, C is a lipid, D is a nucleotide based on common MCQ patterns.
• Select the one with the -CO-NH- structure.

Why B is correct:

• B is a dipeptide, containing the -CO-NH- peptide bond by definition between two amino acids.

Why the others are wrong:

• A lacks peptide bonds as it's a carbohydrate without amino acid linkages.
• C has ester bonds in lipids, not peptide bonds.
• D features phosphodiester bonds in nucleic acids, not peptide bonds.

Not enough information on exact structures, but B fits standard identification.

Final answer: B