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
A person was found dead with bluish green frothy discharge at the angle of mouth and nostrils. What is the diagnosis ? 
Select and explain. 
A. Arsenic poisoning, B. Copper poisoning, C. Mercury poisoning, D. Lead poisoning
B: Copper poisoning
Answer: B: Copper poisoning 
Explanation: Blue green (or purple-green) pigmentation of hair, skin, mucosa and perspiration, purple (blue) green line on gums and bluish green frothy discharge from mouth and nostrils is seen in chronic poisoning of copper salt.