This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nucleotides, Subject name: Biochemistry
[{'content': 'Which of the following amino acid is used in biosynthesis of purines? \nSelect and explain. \nA. Alanine, B. Glycine, C. Threonine, D. Ornithine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Purine Pyrimidine', 'role': 'assistant'}]