Which from following amino acids is an essential amino acid ?

Step-by-step solution

Essential amino acids are those which cannot be synthesized by the human body and must be obtained through diet. The essential amino acids are Valine, Leucine, Isoleucine, Phenylalanine, Methionine, Tryptophan, Threonine, Lysine, Arginine, and Histidine. Among the given options, Phenylalanine is an essential amino acid, while Tyrosine, Glutamine, and Alanine are non-essential amino acids.