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': "Pupil is spared in: \nSelect and explain. \nA. Riley-Day syndrome, B. Disseminated sclerosis, C. Myasthenia gravis, D. Homer's syndrome", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Myasthenia gravis', 'role': 'assistant'}]