This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Physiology
[{'content': 'Respiratory quotient of the brain is? \nSelect and explain. \nA. 0.6-0.7, B. 0.7-0.8, C. 0.8-0.9, D. 0.9-1.0', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. D 0.9-1.0* Respiratory quotient (RQ) is the ratio in the steady state of the volume of carbon dioxide produced to the volume of oxygen consumed per unit time.* RQ of the brain is 0.97-0.99; this is because the principal fuel for the brain is carbohydrates.', 'role': 'assistant'}]