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': 'The following anaesthetic drug causes pain on intravenous adminstration: \nSelect and explain. \nA. Midazolam, B. Propofol, C. Ketamine, D. Thiopentone sodium', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Propofol - Incidence of pain on injection after intravenous administration of drug in small vein (eg. dorsum of wrist or hand) is 80% for etomidate, 40% for propofol, 20% for methohexital 1% and 10% for thiopental 2.5% anesthetic agents - This incidence is greatly reduced if a large vein is used, if a small dose of lidocaine (10mg) is injected sholy before. Thiopental 2.5% also causes pain on IV administration but the incidence is much higher for propofol.', 'role': 'assistant'}]