This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cornea, Subject name: Ophthalmology
[{'content': 'Percentage of endothelial loss in Descemets stripping automated endothelial keratoplasty \nSelect and explain. \nA. 5%, B. 10 - 20%, C. 30 - 40%, D. 50 - 60%', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) 30 - 40%Ref: Cornea: July 2007- Volume 26 - Issue 6 p. 670 - 674)Reported mean endothelial cell loss (usually at 6 months post op) varies from 24-59% (with standard deviations) across the studies.', 'role': 'assistant'}]