This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Toxicology - 3, Subject name: Forensic Medicine
Bluish discoloration of gastric mucosa seen in which poisoning? 
Select and explain. 
A. Mercury, B. Cadmium, C. Amytal sodium, D. Arsenic
C: Amytal sodium
Answer: C: Amytal sodium 
Explanation: POISONS STOMACH MUCOSA Carbolic acid Leathery mucosa Sulphuric acid Black necrotic stomach mucosa Arsenic Red velvety Mucosa Mercury Slate gray Mucosa HNO3 Yellowish Sodium amytal,Copper sulfate Blue