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: Pharmacology
[{'content': 'Mechanism of action of Theophylline in bronchial asthma \nSelect and explain. \nA. Phosphodiestesrase 4 inhibition, B. Beta 2 agonism, C. Antichoinergic action, D. Inhibition of mucociliary clearance', 'role': 'user'}, {'content': "Answer: A \nExplanation: Refer Katzung 11/e p 345 Theophylline is used in bronchial asthma. It's mechanise of action is Inhibition of phosphodiestesrase paicularly PDE-4 Antagonism of adenosine receptors Enhancement for histone deacetylation", 'role': 'assistant'}]