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': 'Increased "Anion gap\' is a characteristic feature \nSelect and explain. \nA. Hyperosmolar non-ketotic diabetic coma, B. Hypoglycaemic coma, C. Phenformin toxicity with coma, D. Renal tubulae acidosis', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]