This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ocular Embryology& Anatomy, Subject name: Ophthalmology
[{'content': 'Structure with highest refractive index: \nSelect and explain. \nA. Cornea, B. Lens, C. Aqueous humor, D. Vitreous humor', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Lens - 1.41 As opposed to maximum refraction taking place at CORNEA - hence maximum Refractive Power Variable Refractive Power -LENS - due to accomodation', 'role': 'assistant'}]