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
Yellow discoloration of skin and mucosa is seen in which poisoning ? 
Select and explain. 
A. Nitrous oxide, B. Nitric acid, C. Sulphuric acid, D. Phosphoric acid
B: Nitric acid
Answer: B: Nitric acid 
Explanation: Nitric acid causes yellow discoloration of the tissues including the crowns of the teeth & yellow stains on the clothing. 
Color of urine is brown.