This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Blood Physiology, Subject name: Physiology
[{'content': 'What function do vitamin B12 and folic acid perform that is critical to hematopoiesis? \nSelect and explain. \nA. Suppo porphyrin production, B. Serve as cofactors for iron uptake, C. Suppo terminal differentiation of erythroid and myeloid cells, D. Suppo production of thymidine triphosphate', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Cell proliferation requires DNA replication, which requires an adequate supply of thymidine triphosphate. Both vitamin B12 and folate are needed to make thymidine triphosphate.', 'role': 'assistant'}]