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: Pharmacology
[{'content': 'Nitrates cannot be used in : \nSelect and explain. \nA. Angina pectoris., B. Billiary colic., C. Renal colic., D. Cyanide poisoning.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Nitrates are not used in renal colic.', 'role': 'assistant'}]