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': 'Marcus Gunn pupil is a feature of: \nSelect and explain. \nA. Optic neuritis, B. Papilledema, C. Ciliary ganglion lesions, D. Lesion of Edinger-Westphal nucleus', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Optic neuritis', 'role': 'assistant'}]