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
The duochrome test is for – 
Select and explain. 
A. Subjective verification of refraction, B. Subjective refinement of refraction, C. Subjective binocular balancing, D. None
B: Subjective refinement of refraction
Answer: B: Subjective refinement of refraction 
Explanation: For subjective refining of sphere following are used:-

(i) The fogging technique 
(ii) Duochrome test 
(iii) Pinhole test