This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
Essential amino acid amongst the following - 
Select and explain. 
A. Valine, B. Lysine, C. Threonine, D. All
D: All
Answer: D: All 
Explanation: Ans. is 4d' i.e.. All Nutritionally Essential Nutritionally Nonessentiai Arginine - semi essential Alanine Histidine Asparagine Isoleucine Asparatate Leucine Cysteine Lysine Glutamate Methionine Glutamine Phenylalanine Glycine Threonine Praline Tryptophan Serine Valine Tyrosine