This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Cancer, Subject name: Pharmacology
[{'content': 'Agent causing hemorrhagic cystitis \nSelect and explain. \nA. Cyclophosphamide, B. Vincristine, C. Cisplatin, D. 5 Fluorouracil', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans: a (Cyclophosphamide)Ref: KD Tripathi, 6th ed. Pg. 822Haemorrhagic cystitis is caused by a metabolite of cyclophosphamide - acrolein If severe, the cystitis may be effectively treated by mesna.Drugs causing Haemorrhagic cystitisIfosfamide Cyclophosphamide Aniline or toluidine derivatives Penicillins - rare Danazol - rare Ifosfamide is the most common cause of haemorrhagic cystitis.', 'role': 'assistant'}]