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
In optic atrophy pallor of the disc is an index of: 
Select and explain. 
A. Degeneration of optic nerve fibres, B. Loss of vasculay of the disc, C. Demyelination of the optic nerve fibres, D. All of the above
B: Loss of vasculay of the disc
Answer: B: Loss of vasculay of the disc 
Explanation: Ans. Loss of vasculay of the disc