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 can result in oral contraceptive failure: 
Select and explain. 
A. Valproate, B. Rifampicin, C. NSAIDs, D. Ethambutol
B: Rifampicin
Answer: B: Rifampicin 
Explanation: Rifampicin can result in failure of oral contraceptives due to its enzyme-inducing property.