Dehydration synthesis forms peptide bonds Steps:

• Amino acids feature a carboxyl group (-COOH) on one and an amino group (-NH₂) on the other.
• The -COOH loses its -OH, and the -NH₂ loses an -H during the reaction.
• These form a water molecule (H₂O) and link as -CO-NH-.
• This condensation releases water, creating the covalent peptide bond.

Why A is correct:

• Peptide bond formation is a condensation reaction where the -OH from the carboxyl group (-COOH) and -H from the amino group (-NH₂) are removed to form H₂O and the amide linkage, per standard biochemical definition.

Why the others are wrong:

• B: Amino group (-NH₂) lacks an -OH; -H comes from -NH₂, not -OH from -NH.
• C: Identical to B; reverses the groups incorrectly, as -COOH provides -OH, not just -H.
• D: Removing O from -COOH disrupts the carbonyl (C=O); -NH₂ loses only one H, not two.

Final answer: A