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
Volume of an adult eyeball is: 
Select and explain. 
A. 7.5 mL, B. 6.5 mL, C. 5.5 mL, D. 8 mL
B: 6.5 mL
Answer: B: 6.5 mL 
Explanation: Ans. 6.5 mL