This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anaesthesia, Subject name: Anaesthesia
[{'content': 'Which of the following is used as preanesthetic medication which causes the longest amnesia? \nSelect and explain. \nA. Midazolam, B. Diazepam, C. Lorazepam, D. Flunitrazepam', 'role': 'user'}, {'content': 'Answer: C \nExplanation: The longest amnesia is produced by lorazepam although half life of lorazepam (15 hours) is shoer than diazepam (36 hours) and this is probably because of its strong receptor binding potential. Its relatively potent amnesic effect, with its anxiolytic and sedative effects, makes lorazepam useful as premedication.', 'role': 'assistant'}]