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
Energy expenditure during normal breathing 
Select and explain. 
A. 25% - 50% of total energy spent, B. 50% - 75% of total energy spent, C. 15% - 20% of total energy spent, D. 2% - 3% of total energy spent
D: 2% - 3% of total energy spent
Answer: D: 2% - 3% of total energy spent 
Explanation: None