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': 'Which one of the following drugs is `Topoisomerase 1 inhibitor ? \nSelect and explain. \nA. Doxorubicin, B. Irinotecan, C. Etoposide, D. Vincristine', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Irinotecan Topoisomerase I inhibitors --> camptothecans (Irinotecan, tropotecan). Topoisomerase II inhibitors Anthracyclines (doxorubicin, daunorubicin) and Epipodophyllotoxin (Etoposid, teniposide).", 'role': 'assistant'}]