This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Optics and Errors of Refraction, Subject name: Ophthalmology
A person came to eye OPD for routine eye check. On snellen's cha he was found to read 6/6 in both eyes. What is the largest approximate distance at which he would be able to read the first topmost letter 
Select and explain. 
A. 36 m, B. 24 m, C. 60 m, D. 1 m
C: 60 m
Answer: C: 60 m 
Explanation: What does 6/6 mean in Snellen's cha * It means that the patient with or without glasses can see the letter at a distance of 6 m which a person normally should have been seeing at 6 m Now you would understand it by next example * 6/12 means a letter which a normal patient should be seeing at 12 metre , this patient can see only when he is nearer, that means 6 metre from Target * 6/60 means that a normal patient should be seeing at 60 metre, but this patient has to be much closer that means 6 metre * This also means that the letter written at 6/60 is big enough that 6/6 vision person can read it at even 60 metre