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: Physiology
[{'content': 'Life span of platelets is: \nSelect and explain. \nA. 120 days, B. 10 days, C. 30 days, D. 60 days', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Platelets are small, granulated bodies that aggregate at sites of vascular injury. They lack nuclei and are 2–4 μm in diameter. There are about 300,000/μL of circulating blood, and they normally have a half-life of about 4 days. The megakaryocytes, giant cells in the bone marrow, form platelets by pinching off bits of cytoplasm and extruding them into the circulation.\nLife span of platelets is around 8-10\xa0 days.\nReference: Ganong’s Review of Medical Physiology T W E N T Y - F I F T H\xa0 \xa0E D I T I O N page no 555', 'role': 'assistant'}]