All of the above are chemical reactions.
If that is a choice
The answer should be A.
Hope this helps :-)
The answer & explanation for this question is given in the attachment below.
Answer:
Amino Acids Are Linked by Peptide Bonds to Form Polypeptide Chains. Proteins are linear polymers formed by linking the α-carboxyl group of one amino acid to the α-amino group of another amino acid with a peptide bond (also called an amide bond).
To form polypeptides and proteins, amino acids are joined together by peptide bonds, in which the amino or NH2 of one amino acid bonds to the carboxyl (acid) or COOH group of another amino acid.
