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: Pathology
[{'content': 'Stain for fat? \nSelect and explain. \nA. Oil red O, B. Sudan black, C. Sudan III, D. Congo red', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Congo redCongo red is not used in lipid staining. It is used in the staining of amyloid protein.", 'role': 'assistant'}]