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
Water content in lens is ? 
Select and explain. 
A. 64%, B. 35%, C. 1%, D. 28%
A: 64%
Answer: A: 64% 
Explanation: Ans. is 'a' i.e., 64% 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%).