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': 'The duochrome test is for – \nSelect and explain. \nA. Subjective verification of refraction, B. Subjective refinement of refraction, C. Subjective binocular balancing, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: For subjective refining of sphere following are used:-\n\n(i) The fogging technique\xa0\n(ii) Duochrome test\xa0\n(iii) Pinhole test', 'role': 'assistant'}]