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 drug used in bronchial asthma needs monitoring: \nSelect and explain. \nA. Theophylline, B. Cromoglycate, C. Salmeterol, D. Terbutaline', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Theophylline', 'role': 'assistant'}]