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': 'A 70 year old patient with benign prostatic hyperplasia underwent transuretheral resection of prostate under spinal anaesthesia. One hour later, he developed vomiting and altered sensorium. The most probable cause is - \nSelect and explain. \nA. Over dosage of spinal anaesthetic agent, B. Rupture of bladder, C. Hyperkalemia, D. Water intoxication', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]