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: Microbiology
[{'content': "Tissue of origin of Kaposi's sarcoma is: \nSelect and explain. \nA. Lymphoid, B. Vascular, C. Neural, D. Muscular", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Vascular', 'role': 'assistant'}]