This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
Which of the following used as preanesthetic medication causes longest amnesia? 
Select and explain. 
A. Midazolam, B. Diazepam, C. Lorazepam, D. Flunitrazepam
C: Lorazepam
Answer: C: Lorazepam 
Explanation: 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.