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
[{'content': 'Allopurinol potentiates the action of : \nSelect and explain. \nA. Corticosteroids, B. Probenecid, C. 6–Mercaptopurine, D. Ampicillin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]