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
Which is the investigation of choice for a spo injury of the knee? 
Select and explain. 
A. Ultrasonography, B. Plain radiography, C. Ahrography, D. Ahroscopy
D: Ahroscopy
Answer: D: Ahroscopy 
Explanation: D i.e. Ahroscopy