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: Surgery
The length of a standard proctoscope is - 
Select and explain. 
A. 4 inches, B. 6 inches, C. 8 inches, D. 3 inches
A: 4 inches
Answer: A: 4 inches 
Explanation: None