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': 'World Health Day is observed every year on \nSelect and explain. \nA. 11-Jan, B. April 7, C. 5-Jun, D. 1-Dec', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]