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: Social & Preventive Medicine
[{'content': 'Each day carrier can carry how many vaccine ls? \nSelect and explain. \nA. 4-Feb, B. 8-Jun, C. 10-Aug, D. 16-20', 'role': 'user'}, {'content': 'Answer: B \nExplanation: A day carrier can carry 6 to 8 vaccine ls. 2 frozen ice packs are used. Vaccines can be stored in aday carrier for a few hours. Ref: Park 21st edition, page 103.', 'role': 'assistant'}]