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': 'After hyperventilation for some time holding the breath is dangerous since \nSelect and explain. \nA. It can lead to CO2 narcosis, B. due to lack of stimulation by CO2, anoxia can go into dangerous level, C. I-0O2 shift 0 dissociation curve to left., D. Alkalosis can lead to tetany', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. Due to lack of stimulation by CO2, anoxia can go into dangerous level', 'role': 'assistant'}]