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
Which of the following drug used against bronchial asthma follows zero order kinetics 
Select and explain. 
A. Salbutamol, B. Phenytoin, C. Tiotropium, D. Theophylline
D: Theophylline
Answer: D: Theophylline 
Explanation: Theophylline follows zero order kinetics, which is used against bronchial asthma.