This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neuro Ophthalmology, Subject name: Ophthalmology
The shown procedure is helpful in diagnosing? 
Select and explain. 
A. Adies pupil, B. Horner's pupil, C. Marcus Gunn Pupil, D. Pin point pupil
C: Marcus Gunn Pupil
Answer: C: Marcus Gunn Pupil 
Explanation: Procedure shown is Swinging Flashlight test : used for diagnosis of Marcus Gunn Pupil Relative afferent pupilary defect (RAPD) Or Marcus Gunn Pupil Site of Lesion Causes Pupil at Presentation Light Reflex Special Points Retina or optic nerve -Incomplete optic nerve lesion -Optic neuritis -CRAO/CRVO -Retinal detachment -IsocoriaEqual pupil size in both eyes -Incomplete optic nerve lesion -Optic neuritis -Light on normal eye (LE) Both pupil constrict -Light on Abnormal eye (RE) Both pupil dilate PARADOXICAL DILATATION Pupillary Escape phenomenon (dilatation produced by withdrawing light from normal eyes outweighs constriction by abnormal eye) Swinging Flashlight test is done for Diagnosis -Leads to fatigue of neural tissue -Earlier on the side of lesion