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: Medicine
[{'content': 'Imatinib mesylate is most useful in the treatment of- \nSelect and explain. \nA. Chronic lymphoid leukaemia, B. Chronic myeloid leukaemia, C. Acute myeloid leukaemia, D. Acute lymphoid leukaemia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]