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: Biochemistry
Essential amino acid is ? 
Select and explain. 
A. Alanine, B. Serine, C. Arginine, D. Proline
C: Arginine
Answer: C: Arginine 
Explanation: Ans. is 'c' i.e., Arginine Nutritionally Essential Nutritionally Nonessential Arginine Alanine Histidine Asparagine Isoleucine Leucine Asparatate Lysine Cysteine Methionine Phenylalanine Glutamate Threonine Tryptophan Valine Glutamine Glycine Proline Serine Tyrosine