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
Which does not handle free radicals inside lens- 
Select and explain. 
A. Vitamin A, B. Vitamin C, C. Vitamin E, D. Catalase
A: Vitamin A
Answer: A: Vitamin A 
Explanation: Emzymatic antioxidant mechanisms :- Reduced glutathioe (most impoant), glutathione peroxidase, superioxide dismutase, catalase. Non-enzymatic defence mechanisms :- Vitamin C, Vitamin E, and possibly carotenoids. Ref: Various textbooks.