This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
The anterior focal length of the schematic eye is: 
Select and explain. 
A. 15.7 mm, B. 17.2 mm, C. 13 mm, D. None of the above
B: 17.2 mm
Answer: B: 17.2 mm 
Explanation: Ans. 17.2 mm