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': 'WHO formation day is – \nSelect and explain. \nA. 5th may, B. 7th April, C. 10th june, D. 10th july', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The constitution came into force on 7th April 1948, which is celebrated every year as world health day.', 'role': 'assistant'}]