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
Alkylating agents include : a) Doxorubicin b) Chlorambucil c) Vinblastine d) Busulfan e) Methotrexate 
Select and explain. 
A. ace, B. bd, C. bc, D. ad
B: bd
Answer: B: bd 
Explanation: None