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': 'Amaurosis fugax is due to- \nSelect and explain. \nA. TIA, B. Tobacco, C. Optic neuritis, D. Papilloedema', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Amaurosis fugax is sudden temporary and painless loss of vision due to transient failure of retinal circulation.\nIt may occur in carotid transient ischemic attack (TIA).', 'role': 'assistant'}]