This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Optics and Errors of Refraction, Subject name: Ophthalmology
Maximum refraction is done by: 
Select and explain. 
A. Anterior surface of lens, B. Posterior surface of lens, C. Anterior surface of cornea, D. Posterior surface of cornea
C: Anterior surface of cornea
Answer: C: Anterior surface of cornea 
Explanation: Power of eye is contributed by surfaces where refraction of light occurs as it traverses from the external environment to the retina. These are: - Anterior surface of cornea ( max contribution) - Posterior surface of cornea - Anterior surface of lens - Posterior surface of lens