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: Physiology
[{'content': 'Mouth-to-mouth respiration provides an oxygen concentration of: \nSelect and explain. \nA. 16%, B. 20%, C. 22%, D. 24%', 'role': 'user'}, {'content': "Answer: A \nExplanation: A i.e. 16%Mouth - to mouth respiration provides 16% of 02.In mouth- to - mouth respiration the resuscitor takes a deep breath & exhales into the subject's mouth. It provides 16% (15.7%) of 02.(amount of 02 that is present in expired air)", 'role': 'assistant'}]