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': 'Shelf life of blood in a blood bank in CPDA buffer \nSelect and explain. \nA. 21 days, B. 30 days, C. 35 days, D. 42 days', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Answer- C. 35 daysCitrate phosphate dextrose-adenine (CPD-A )- 35 days', 'role': 'assistant'}]