This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pathology
Highest refractory of index is at 
Select and explain. 
A. Ant surface of cornea, B. Post surface of cornea, C. Center of lens, D. Posterior capsule of lens
C: Center of lens
Answer: C: Center of lens 
Explanation: .