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: Surgery
[{'content': 'Best for staging anal Ca. Is \nSelect and explain. \nA. MRI, B. PET CT, C. CECT, D. Transrectal usg + DRE', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Overall best for staging is PET CT.\nFor T stage transrectal usg is used.', 'role': 'assistant'}]