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': "In chronic simple glaucoma the most common field defect is: \nSelect and explain. \nA. Arcuate field defect, B. Baring of blind spot, C. Bjerrum scotoma, D. Siedel's sign", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. Baring of blind spot', 'role': 'assistant'}]