This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Lens, Subject name: Ophthalmology
The water content in the lens is 
Select and explain. 
A. 1%, B. 28%, C. 35%, D. 64%
D: 64%
Answer: D: 64% 
Explanation: (Refer: AK Khurana Comprehensive Ophthalmology, 6th edition, pg no. 181)The lens is composed of 64% water, 35% protein, and 1% lipid, carbohydrate and trace elements. The protein concentration in the lens is actually the highest amongst body tissues. The main types of proteins are alpha (31%), beta (55%) and gamma (2%) crystallins, and insoluble albuminoids (12%)