This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Chemotherapy, Subject name: Pharmacology
Which of the following drugs is Topoisomerase 1 inhibits 
Select and explain. 
A. Doxorubicin, B. Irinotecan, C. Etopside, D. Vincristine
B: Irinotecan
Answer: B: Irinotecan 
Explanation: Refer KDT 6/e p 825, Camptothecin derivatives like topotecan and irinotecan act by inhibiting Topoisomerase -1whereras epipodophylotoxins and anthracycline act by inhibiting Topoisomerase -2