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
For biometric studies of the eyeball best pulse echo technique on ultrasonography is: 
Select and explain. 
A. A Scan, B. B Scan, C. C Scan, D. All of the above
A: A Scan
Answer: A: A Scan 
Explanation: Ans. A Scan