Respuesta :
Answer:
The R-group
Explanation:
Amino acids are organic compounds that combine to form proteins. There are 20 of them, out of which 9 are essential. All of them have a similar structure: they consist of an alpha (α) carbon atom bonded to an amino group (NH2), a carboxyl group (COOH), a hydrogen atom, and an R group. The R group is the organic component, a side chain, that is unique to each amino acid.
This is why the first option is the correct one.