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
Marcus Gunn pupil is a feature of all, EXCEPT: 
Select and explain. 
A. Optic neuritis, B. Papilloedema, C. Optic atrophy, D. Retinal detachment
B: Papilloedema
Answer: B: Papilloedema 
Explanation: Marcus Gunn Pupil: In swinging flashlight test, the pupil on the diseased side dilates on transferring light to it. It is positive in the following cases: Optic neuritis Optic atrophy Retinal detachment Central retinal vein occlusion Central retinal aery occlusion Ref: Review of ophthalmology A.K.Khurana, 5Th Ed, page 22.