The correct option is
C i - Alanine, ii Glycine, iii Serine
The amino acid is the basic units of proteins and is formed by one carboxyl bond plus one amine group on the side chain.
On the basis of the compound present, they are divided into various types, for example, simple amino acid, sulphur containing amino acids, basic amino acids, an aromatic amino acid.
On the given structure CH3 is present on the side chain, and here the amino acid is alanine and in the second image hydrogen is present as the side chain and so it is the simplest amino acid that is glycine.
On the third chain, CH₂OH is present and the amino acid is serine.
So, the correct option is 'i - Alanine, ii Glycine, iii Serine'