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: Forensic Medicine
Purple lining over gums is seen in which chronic poisoning: 
Select and explain. 
A. Magnesium, B. Lead, C. Copper, D. Mercury
C: Copper
Answer: C: Copper 
Explanation: C i.e. Copper