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
Which of the following poison causes cherry-red -color postmoem staining? 
Select and explain. 
A. Carbon monoxide, B. Aniline, C. Phosphorus, D. Nitrites
A: Carbon monoxide
Answer: A: Carbon monoxide 
Explanation: A cherry-red colouration of the skin, mucous membranes, conjunctiva, nail beds, areas of hypostasis, blood, tissues and internal organs is seen in carbon monoxide (CO) poisoning. It is associated with 30-40% COHb. Ref: The Essentials of Forensic Medicine and Toxicology by Narayan Reddy, 27th edition, Page 555.