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
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 - 
Select and explain. 
A. Over dosage of spinal anaesthetic agent, B. Rupture of bladder, C. Hyperkalemia, D. Water intoxication
D: Water intoxication
Answer: D: Water intoxication 
Explanation: None