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
Pupil is spared in: 
Select and explain. 
A. Riley-Day syndrome, B. Disseminated sclerosis, C. Myasthenia gravis, D. Homer's syndrome
C: Myasthenia gravis
Answer: C: Myasthenia gravis 
Explanation: Ans. Myasthenia gravis