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 can lead to increased level of Theophylline 
Select and explain. 
A. Rifampicin, B. Phenobarbitone, C. Cimetidine, D. Phenytoin
C: Cimetidine
Answer: C: Cimetidine 
Explanation: Cimetidine is an enzyme inhibitor which can increase theophylline levels and lead to toxicity.