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: Dental
Helium-neon (HeNe) Lasers are example for 
Select and explain. 
A. Excimer lasers, B. Gas lasers, C. Diode lasers, D. Solid state lasers
B: Gas lasers
Answer: B: Gas lasers 
Explanation: None