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': 'Magnesium deficiency is caused by -a) Prolonged artificial ventilationb) Small bowel resectionc) Renal diseased) Liver cirrhosis \nSelect and explain. \nA. a, B. c, C. ac, D. bc', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]