This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Physiology
[{'content': 'Cut off limit for deoxygenated hemoglobin for appearance of cyanosis is? \nSelect and explain. \nA. >4 gm%, B. >5 gm%, C. < 2 gm%, D. <4 gm%', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B >5gm%Ref: Ganong, 25th ed. pg. 642Cyanosis appears whenever the magnitude of reduced hemoglobin level of blood in capillaries is >5 gm%.', 'role': 'assistant'}]