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': 'Most common cause of bilateral internuclear ophthalmoplegia is \nSelect and explain. \nA. Quinine toxicity, B. Diphtheria, C. Multiple sclerosis, D. Diabetes mellitus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: U/L INO - Diabetes mellitus.\nB/L INO - Multiple sclerosis.', 'role': 'assistant'}]