This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Special Senses, Subject name: Physiology
Total dioptric power of the crystalline lens inside the eye is: 
Select and explain. 
A. 41 D, B. 18 D, C. 59 D, D. 72 D
B: 18 D
Answer: B: 18 D 
Explanation: Diopteric power of the crystalline lens is +18 D. Total refractive power of the entire eye is +59 D; most of the refraction occurs at the anterior surface of the cornea (41 D).