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
Best investigation to diagnose piles is - 
Select and explain. 
A. Proctosigmoidoscopy, B. Barium enema, C. Ultrasound, D. Proctoscopy
D: Proctoscopy
Answer: D: Proctoscopy 
Explanation: None