Correct Answer: A
Explanation:
In amino acids four different groups attached to the same carbon atom (apart from glycine), that’s these are chiral. The lack of a plane of symmetry means that there will be two stereoisomers of an amino acid (apart from glycine) - one the non-superimposable mirror image of the other. For a general 2-amino acid, the isomers are:
All the naturally occurring amino acids have the right-hand structure in this diagram. This is known as the "L-" configuration. The other one is known as the "D-" configuration.