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
All of the following are essential aminoacids except: 
Select and explain. 
A. Methionine, B. Lysine, C. Alanine, D. Leucine
C: Alanine
Answer: C: Alanine 
Explanation: Threonine, Lysine, Phenylalanine, Methionine, Isolcucine & Leucine, Tryptophan, Valine > Histidine >> Arginine are nutritionally essential amino acids. Among these last two (histidine & arginine) are semi- essential, and arginine is more essential than histidine.