This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous System, Subject name: Physiology
[{'content': 'The brain neurons may get irreversibly damaged if exposed to significant hypoxia for: \nSelect and explain. \nA. 8 minutes., B. 20 min, C. 5 sec., D. 15 sec', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. 8 minutes.The cerebral cortex can tolerate the acute hypoxia due to complete circulatory arrest for 5-10 min at 28deg C, 20 min at 20deg and 50 min at 15degC', 'role': 'assistant'}]