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: Pathology
[{'content': 'Megaloblastic anaemia occurs due to \nSelect and explain. \nA. Iron deficiency, B. Folate deficiency, C. Vitamin C deficiency, D. Protein deficiency', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]