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: Unknown
This laser is ? 
Select and explain. 
A. Ruby, B. CO2, C. YAG, D. Argon
C: YAG
Answer: C: YAG 
Explanation: Nd: YAG lasers are used to make a non-invasive opening in the after cataract.