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
In an aphakic eye the anterior focal point from the anterior surface of cornea is about: 
Select and explain. 
A. 15 mm, B. 21 mm, C. 23 mm, D. 31 mm
C: 23 mm
Answer: C: 23 mm 
Explanation: Ans. 23 mm