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: Anatomy
[{'content': 'In a chronic smoker a highly malignant aggressive and metastatic lung carcinoma is \nSelect and explain. \nA. Small cell carcinoma, B. Squamous cell carcinoma, C. Large cell carcinoma, D. Adenocarcinoma', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Cigarette smoking is most strongly associated with squamous cell carcinoma and small cell carcinoma. Small cell carcinoma variant is more malignant and metasizes Ref Harrison 19th edition pg 1702', 'role': 'assistant'}]