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: Pharmacology
[{'content': 'Which of the following drug used against bronchial asthma follows zero order kinetics \nSelect and explain. \nA. Salbutamol, B. Phenytoin, C. Tiotropium, D. Theophylline', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Theophylline follows zero order kinetics, which is used against bronchial asthma.', 'role': 'assistant'}]