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
Circumference of an adult eyeball is: 
Select and explain. 
A. 80 mm, B. 65 mm, C. 75 mm, D. 70 mm
C: 75 mm
Answer: C: 75 mm 
Explanation: Ans. 75 mm