As shown in Figure 1, an amino acid must have which of the following properties in order to be incorporated into a polypeptide? A:
The ability to remain stable in the presence of water molecules
B:
An R-group that is compatible with the R-group of the last amino acid incorporated
C:
A central carbon atom that reacts with a nitrogen atom to form the peptide bond
D:
The ability to form a covalent bond with both its NH2 group and its COOH group

There is a photo if it would help you
Thanks;)