This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Non communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'WHO definition of blindness \nSelect and explain. \nA. <6/60, B. <3/60, C. <6/18, D. <6/9', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Legal blindness Is defined as visual acuity (vision) of 3/60 or less in the better eye with best correction possible In many areas, people with average acuity who nonetheless have a visual field of less than 10 degrees (the norm being 180 degrees) are also classified as being legally blind Ref: New Guidelines, NPCB, GOI 2017-18', 'role': 'assistant'}]