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': 'Campimetry (Scotometry) is performed in the visual field area of: \nSelect and explain. \nA. 50deg, B. 30deg, C. 60deg, D. 90deg', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. 30deg', 'role': 'assistant'}]