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: Surgery
[{'content': 'Which of the following subtype of lung carcinoma produces superior vena cava syndrome:September 2009 \nSelect and explain. \nA. Small cell carcinoma, B. Adenocarcinoma, C. Anaplastic carcinoma, D. Squamous cell carcinoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A: Small cell carcinoma', 'role': 'assistant'}]