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
[{'content': 'Greenish discolouration at putrefaction is due to? \nSelect and explain. \nA. MetHb, B. Sulph-meth Hb, C. Deoxy Hb, D. Carboxy Hb', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Sulph-meth Hb", 'role': 'assistant'}]