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
Anticancer drugs of plant origin is/are :  a) Vincristine b) Isotretinoin c) Bleomycin d) Methotrexate 
Select and explain. 
A. ac, B. a, C. b, D. ab
D: ab
Answer: D: ab 
Explanation: None