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
Brown skin cornea is seen in: 
Select and explain. 
A. Siderosis, B. Mustard gas exposure, C. Chalcosis, D. All
D: All
Answer: D: All 
Explanation: A i.e. Siderosis; B i.e. Mustard gas exposure; C i.e. Chalcosis