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
[{'content': 'The arrow marked sign is due to deposition of \nSelect and explain. \nA. Copper, B. Melanin, C. Iron, D. Magnesium', 'role': 'user'}, {'content': "Answer: C \nExplanation: lron deposition anterior to advancing head of pterygium is called as Stocker's line.", 'role': 'assistant'}]