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 factory worker presents with excessive salivation, blue lines on gums, tremors, disturbed personality, insomnia and loss of appetite. The most likely poisoning is: 
Select and explain. 
A. Mercury, B. Lead, C. Arsenic, D. Phosphorus
A: Mercury
Answer: A: Mercury 
Explanation: A i.e. Mercury