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
Greenish discolouration at putrefaction is due to? 
Select and explain. 
A. MetHb, B. Sulph-meth Hb, C. Deoxy Hb, D. Carboxy Hb
B: Sulph-meth Hb
Answer: B: Sulph-meth Hb 
Explanation: Ans. is 'b' i.e., Sulph-meth Hb