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
Foldable lesn is made up of - 
Select and explain. 
A. PMMA, B. Silicon, C. Hydrogel, D. None
B: Silicon
Answer: B: Silicon 
Explanation: (IOL are made of (i) PMMA (ragid IOL); (ii) Silicon, acrylic, hydrogel, collamer (foldable IOL). Ref: Khurana 7th/e p.213 & 4th/e p.195)