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
Action of theophylline is reduced by ? 
Select and explain. 
A. Smoking, B. Erythromycin, C. Cimetidine, D. Lithium
A: Smoking
Answer: A: Smoking 
Explanation: Ans. is 'a' i.e., Smoking