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
The arrow marked sign is due to deposition of 
Select and explain. 
A. Copper, B. Melanin, C. Iron, D. Magnesium
C: Iron
Answer: C: Iron 
Explanation: lron deposition anterior to advancing head of pterygium is called as Stocker's line.