This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
[{'content': 'Nitrogen atoms in purines are derived from all except \nSelect and explain. \nA. Aspaate, B. Glutamine, C. THF, D. Glycine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The N atoms at positions 3 and 9 are derived from the amide nitrogen glutamine Ref-Sathyanarayana 4/e', 'role': 'assistant'}]