Answer:
The correct answer option is 3. amino acid.
Step-by-step explanation:
Amino acids are the organic compounds that contain amine (-NH2) and carboxyl (-COOH) functional groups.
While a polymer is made up of a chain of monomers where the monomer is an amino acid. So when you have more number of amino acids, a polymer is formed.
It means that amino acid alone on its own is not a polymer.
Therefore, the correct answer option is 3. amino acid, rest all options are polymers.