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: Dental
An average diameter of apical foramen in patients of age above 55 years is 
Select and explain. 
A. 400 micrometer, B. 502 micrometer, C. 681 micrometer, D. 602 micrometer
C: 681 micrometer
Answer: C: 681 micrometer 
Explanation: None