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: Medicine
[{'content': 'Minimum concentration of reduced hemoglobin required for cyanosis is - \nSelect and explain. \nA. 1 gm/dl, B. 3gm/dl, C. 7gm/dl, D. 9gm/dl', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]