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 dead body is having cadaveric lividity of greenish-purple colour. The most likely cause of death is by poisoning due to: 
Select and explain. 
A. Hydrocyanic acid, B. Hydrogen sulphide, C. Oleander, D. Sodium nitrite
B: Hydrogen sulphide
Answer: B: Hydrogen sulphide 
Explanation: Post moem appearances of hydrogen sulphide (H2S) poisoning: Rotten egg odour General signs of asphyxia The colour of the blood and viscera and bronchial secretions is greenish-purple. In hydrocyanic acid poisoning the colour is bright red. In poisoning by nitrites, potassium chlorate, potassium bicarbonate, nitrobenzene, acetanilide, bromates, and aniline the colour is chocolate or copper brown. There is no characteristic appearance in oleander poisoning. Ref: Textbook of Forensic Medicine and Toxicology by K S Narayan Reddy, 27th edition, Page 557.