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: Pathology
[{'content': 'Retention of mature neutrophils in bone marrow is known as: \nSelect and explain. \nA. Myelokathesis., B. Myelocytosis, C. Leukocytosis, D. Leukemia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]