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
Which of these amino acids does not have asymmetric carbon atom? 
Select and explain. 
A. Valine, B. Glycine, C. Alanine, D. Tryosine
B: Glycine
Answer: B: Glycine 
Explanation: Glycine is the simplest amino acid with no optical activity.