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: Medicine
[{'content': 'Which of the following is the first strategy in the management of chronic obstructive lung disease ? \nSelect and explain. \nA. Aminophylline, B. Anti-cholinergics, C. Cessation of smoking, D. Oral steroids', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]