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: Ophthalmology
[{'content': 'Normal visual acuity of 6/6 is achieved by the age of: \nSelect and explain. \nA. 2 years, B. 3 years, C. 5 years, D. 7 years', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. 3 years Full visual acuity (6/6) is attained by 3 years of age. Age Visual acuity New born 6/240 1 month 6/180- 6/90 4-6 months 618- 6/9 3 years 6/6', 'role': 'assistant'}]