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: Medicine
[{'content': 'ECG changes of hypomagnesemia is: March 2004 \nSelect and explain. \nA. Decreased QT interval, B. Increased QT interval, C. Greatly increased PT interval, D. Tall T waves', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B i.e. Increased QT interval', 'role': 'assistant'}]