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: Ophthalmology
Lens has a respiratory quotient of: 
Select and explain. 
A. 1, B. 0.6, C. 0.7, D. 0.9
A: 1
Answer: A: 1 
Explanation: Ans. 1