This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abnormalities of Corneal Transparency, Subject name: Ophthalmology
KF ring has deposition of which of the following in the Descemet's membrane? 
Select and explain. 
A. Copper, B. Arsenic, C. Iron, D. Mercury
A: Copper
Answer: A: Copper 
Explanation: Ans. is 'a' i.e., Copper Kayser-Fleischer (KF) ring - Copper deposition in Chalcosis or Wilson's disease Fleischer ring - Deposition of iron and is a sign of keratoconus