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': 'Vitamin B 12  deficiency is likely to cause - \nSelect and explain. \nA. Bitemporal hemianopia, B. Binasal hemianopia, C. Heteronymous hemianopia, D. Centrocecal scotoma', 'role': 'user'}, {'content': 'Answer: D \nExplanation: The predominant cause of nutritional optic neuritis is thought to be deficiency of B - complex vitamins, particularly thiamin (vitamin B1) and cyanocobalamin (Vitamin B12). Deficiency of pyridoxin (vitamin B6), niacin (vitamin B3), riboflavin (vitamin B2), and / or folic acid also seems to play a role.\nMost common visual field defect is central or centrocaecal scotoma.', 'role': 'assistant'}]