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': 'Cause of atonic bladder is: \nSelect and explain. \nA. Injury to sacral plexus, B. Injury to upper thoracic cord, C. Pregnancy, D. UTI', 'role': 'user'}, {'content': 'Answer: A \nExplanation: A i.e. Injury to sacral plexus', 'role': 'assistant'}]