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: Anaesthesia
[{'content': 'All are true about thiopentone except – \nSelect and explain. \nA. NaHCO3 is a preservative, B. Contraindicated in porphyria, C. Agent of choice in shock, D. Has cerebroprotective action', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Thiopentone causes hypotension → contraindicated in shock & hypotensive states.', 'role': 'assistant'}]