This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
[{'content': 'Open Vial Policy apply to which vaccine \nSelect and explain. \nA. Measles, B. BCG, C. Japanese encephalitis vaccine, D. Hepatitis B', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The WHO multi-dose l policy states that ls of liquid DTP, TT, HepB and OPV opened in a fixed clinic may be used at more than one immunization session provided that: A) The expiry date has not passed. B) The vaccines are stored under appropriate cold chain conditionsPark pg no: 117', 'role': 'assistant'}]