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: Pathology
[{'content': 'ACTH producing lung carcinoma \nSelect and explain. \nA. Small cell CA, B. Squamous cell CA, C. Mesothelioma, D. Bronchoadenocarcinoma', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Small cell carcinoma", 'role': 'assistant'}]