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
Failure of oral contraceptives occur when used with any of these except: 
Select and explain. 
A. Asprin, B. Tetracycline, C. Phenytoin, D. Rifampicin
A: Asprin
Answer: A: Asprin 
Explanation: None