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 increase activity ofwarfarin? 
Select and explain. 
A. OCP, B. Cimetidine, C. Griseofulvin, D. Phenytoin
B: Cimetidine
Answer: B: Cimetidine 
Explanation: Ans. is 'b' i.e., Cimetidine