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 are not used in? \nSelect and explain. \nA. CHF, B. Cyanide poisioning, C. renal colic, D. Esophageal spasm', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C; renal colic', 'role': 'assistant'}]