This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Medicine
[{'content': 'Which of the following tumor is most commonly associated with superior vena cava syndrome \nSelect and explain. \nA. Lymphoma, B. Small cell carcinoma, C. Non small cell carcinoma, D. Metastasis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Small cell carcinomas are central or hilar in location and are highly associated with superior vena caval syndrome and paraneoplastic syndrome. Ref:Harsh Mohan-Pathology-6th edition,page no:500.', 'role': 'assistant'}]