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: Physiology
[{'content': 'Megaloblasts are precursors of: \nSelect and explain. \nA. Megakaryocytes, B. Normoblasts, C. Myelocytes, D. Macrocytes', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]