This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intravenous Anesthetic Agents, Subject name: Anaesthesia
[{'content': 'All true about accidental intra aerial injection of Thiopentone except:- \nSelect and explain. \nA. Immediate intense vasoconstriction and excruciating pain, B. Cause is precipitations of thiopental crystals in the aerial vassals, C. To relieve pain we have to immediately remove the misplaced aerial cannula., D. Sympathectomy of the upper extremity produced by Stellate ganglion block may relieve vasoconstriction.', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The accidental intra aerial injection of drug due to wrongly placed cannula M/N 1. Leave the cannula in situ 2. Intra aerial injection of heparin 3. Lidocaine, papaverine phenoxybenzamine injected 4. Stellate ganglion block', 'role': 'assistant'}]