This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Medicine
[{'content': 'Most common site of histiocytosis is - \nSelect and explain. \nA. Bone, B. Skin, C. Lung, D. Liver', 'role': 'user'}, {'content': "Answer: A \nExplanation: Langerhan's cell histiocytosis are malignant proliferation of dendritic cells or macrophages. These proliferating cells are actually Langerhan's cells of marrow origin.Reference :Harsh Mohan textbook of pathology 6th edition pg no 385.", 'role': 'assistant'}]