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': 'An example of chronic myeloproliferative disorder is - \nSelect and explain. \nA. Neutrophilic leukaemoid reaction, B. Essential thrombocythaemia, C. Plasmacytosis, D. Hairy cell leukaemia', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]