The correct option is B Essential
Amino acids which cannot be synthesized by animals through transformation or transamination and get supplement from outside are called essential amino acids. These amino acids must be present in the diet. Among 20 amino acids only 9, amino acids are essential. Leucine, isoleucine, tryptophan, phenylalanine, lysine, methionine, valine and threonine are essential amino acids. Thus, the correct answer is B.