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
[{'content': 'Which of the following is an optically inactive amino acid? \nSelect and explain. \nA. Threonine, B. Tyrosine, C. Glycine, D. Serine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Optical properties: All the amino acids except glycine possess optical isomers due to the presence of asymmetric carbon atom.\nRef: Satyanarayan 3rd edition page no: 49', 'role': 'assistant'}]