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
Following are polar amino acids, except: 
Select and explain. 
A. Isoleucine, B. Serine, C. Arginine, D. Histidine
A: Isoleucine
Answer: A: Isoleucine 
Explanation: Isoleucine