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
Optically inactive Amino Acid is 
Select and explain. 
A. Proline, B. Glycine, C. Lysine, D. Leucine
B: Glycine
Answer: B: Glycine 
Explanation: Asymmetric (chiral) carbon is responsible for optical activity.
Glycine does not have asymmetric carbon, therefore is optically inactive.