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 average distance of the fovea from the temporal margin of the optic disc is – \nSelect and explain. \nA. 1 disc diameter, B. 2 disc diameter, C. 3 disc diameter, D. 4 disc diameter', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Foveola of fovea is situated about 2 disc diameter (3 mm) temporal to the temporal margin of optic disc.', 'role': 'assistant'}]