The correct option is D Serine
Serine is an amino acid having hydroxyl group in its side chain, thus it is a polar amino acid. The chemical formula of serine is HOOC-CH(NH2)-CH2OH. This structure will be called 2-Amino-3 hydroxy propionic acid meaning that starting from the carboxylic carbon (carbon atom number one) at second carbon there is one amino group present and at the third carbon there is one hydroxyl group present in a molecule of propionic acid.