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
According to WHO , blindness is defined as a visual acuity of the better eye, less than - 
Select and explain. 
A. Jun-60, B. May-60, C. Apr-60, D. Mar-60
D: Mar-60
Answer: D: Mar-60 
Explanation: <p> WHO defines blindness if the visual acuity is less than 3/60. Reference:Park&;s textbook of preventive and social medicine,K.Park,23rd edition,page no:401. <\p>