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
Investigation for injury of knee cailage 
Select and explain. 
A. Aspiration, B. Ahrography, C. X-ray, D. Ahroscopy
D: Ahroscopy
Answer: D: Ahroscopy 
Explanation: D i.e. Ahroscopy